Duo to the Death

Blokus has taken over my life

XF Rubik, two lines of defence

Posted by nand on April 6, 2010

XF Rubik is one of the two most frustrating openings to play against (the other being XF Lerpy) since (1) there are some well-mapped lines that violet can play automatically to win by a good-to-excellent margin and (2) it’s not obvious what to do to make the loss at least up-for-grabs rather than inevitable if violet is at least moderately competent (or has a memory stocked with the more common lines). Anyway, here are two lines of defence that I think were examined a year or two ago, discarded, but have been revived. Like most old/new lines they may be flawed but since the exact reasons why they are flawed are now forgotten (or were worked out by players who are no longer frequenters of the site) and since blokus strategy has gotten subtler over the years, they are definitely worth a second look. At the moment they’re having a lot of success on the site but… well, now I’ve written a post I’m expecting that they will get a little less successful.

Variant 1:

Variant 2:

The bottom one looks better, since the 1-2 series of holes created to the left of orange F is something one instinctively avoids in duo. Yet the first one does force violet to play the ugly I5 on left if he wants to stretch past it. The good thing about both of these ones is that violet F is easily cut off & so violet is tempted to defend on right on move 3, & if that occurs orange has a lot of strong moves on the left (probably Y or L5), & I think the game is orange’s to win then. But I think the circling game doesn’t look great for orange: here’s a line that works with either positioning of orange F:

(Note that if orange plans to block on the bottom on turn 4, then orange Y should probably be L5 or even a kiss move like T4 or T5. But that looks kinda suicidal to me.) Anyway, so violet’s got two perfect series of jaggies for orange to climb over, & meanwhile violet has lots of nice moves on either side: Z5 or W on bottom, L5 kiss or hang on top. Am I missing something or is this a writeoff?

Posted in openings, XF Rubik | 4 Comments »

Oldmanc (backstepped) F, close-X line 1

Posted by nand on April 1, 2010

Here’s a line I’ve used a lot lately with a fair amount of success.  I think it’s probably flawed but because the flaw comes in the midgame not early on it takes a very shrewd or lucky violet player to see the problems here.

If violet blocks on the bottom this is an easy win for orange–play N on the top (F12rrur) & violet’s defence crumbles. The tricky part comes if violet instead blocks with V5(H12uurr) or T5(H12uur), because the blocking in orange’s area is really awful–you basically end up giving away at least a 4-piece &/or being forced to use the I1. That said, I think this line is worth exploring further. Orange’s continuation on the bottom is of course Z5 or T5–I think Z5 is better but have not conclusively proven this.

Posted in blokus, Oldmanc backstepped F, openings | Leave a Comment »

Duo Freestyle

Posted by nand on March 11, 2010

I talked to pentti today & he (uh, assume it’s a “he”, pentti…? :)) tells me that with modifications the freestyle idea is feasible for duo also. Player A picks pieces for both colours (violet and orange); Player B decides whether to play violet or orange.  (I suspect that one should further refine this by permitting specification of exact positions for pieces if Player A wishes–this would be key for X and F openings.) Worth trying out. The best thing about this is that it would open up a lot of mirrorable first moves, as Player A can specify a non-mirror reply.

Posted in blokus, variants | Leave a Comment »

Blokus variants

Posted by nand on March 5, 2010

Because blokus in its various forms is (1) deterministic (no random or hidden element in play) and (2) weighted towards one player (the one who moves first), there have been various efforts at devising variants that would compensate for those characteristics.

There are many possible trivial changes–e.g. moving the starting locations of pieces–which don’t seem to me very interesting.  But there are 3 major ones that are of serious interest.

1) Freestyle

This was devised, I’m told, by Bernard Tavitian himself (creator of blokus). Though in principle it could be used for any Blokus variant, I’ve rarely encountered it with Duo; it has however become the standard means of play among top-level C2 players. (I can’t vouch for Trigon as I never play or watch it.)

The idea is that there’s a preliminary round before actual play begins. Player A names two starting pieces for blue and red to play. Player B then has the option of either (1) taking blue & red & being required to use those pieces on his first move with each colour; or (2) ceding first-move advantage to Player A; Player A then is required to play the pieces he/she named.

The beauty of this variant is that it gets away from predictable openings without totally changing game play. Player A will not name a standard, powerful opening (e.g. L5/N), because then this is just handing that advantageous opening to Player B. But neither will Player A name something absurdly weak (e.g. I1/O4) as then Player B will surely decline it & Player A will be stuck playing that absurdly weak opening as blue/red. So Player A will name something that’s neither overpoweringly good nor obviously wrong.

Though this solution could be used for Duo, I think it tends to be disfavoured because the game has so little margin for error or less-than-optimal play. Nonetheless, I think it would be worth experimenting with. So if anyone wants to give it a whirl with me….. I think this would probably require some further refinement, since whereas with C2 placement of the first pieces has little scope for choice (since two sides of each starting corner are blocked off), with Duo’s mid-board starting points you could play an optimal piece in less-than-optimal conditions. (For instance, Player A would be foolish to call out “X”. But he could certainly call out “X with centre on the dot” & that would be a good call: neither a terrible opening nor a totally strong one.)

2) Glofus

Not sure who thought of this one, or who thought up the name. It’s the most obvious but least interesting variant: whoever gets fewest rather than most points wins.  One big disadvantage of this one is that it can only be played in Training, since the software won’t recognize this variant & will thus dock points from the “winner” rather than the “loser” of a game of Glofus. — Experience shows that orange can usually win this one without much trouble, as you’d expect; possibly if people worked harder on strategy then it would be easier to devise ways to win as violet, but I don’t think this variant is interesting enough that anyone will put the necessary time in to do this. It’s more of a stunt or a pass-the-time amusement.

3) Forza

This one is devised by a player called pentti79. I’ve encountered it with Duo, but there’s no reason it couldn’t be used in C2 or Trigon too. The rules are simple: you are only allowed to play a piece named by your opponent, but you can play it wherever you like. In addition (to avoid running down your opponent’s clock unfairly), you must place the piece AFTER you name the piece your opponent must play on the next turn. (Thus this game is not amenable to very short clock times–like 5 minutes–as you need to allow for time to type piece-names; this is especially crucial in endgames as there is only one clock running then, & the endgame is of course dictated by the player who runs out of pieces first.)

This sounds awkward and silly, but it’s actually a fascinating twist to the game and deserves to become a more widespread variant. The amount of pretzel-logic required to see ahead even two moves is quite formidable, and while I imagine that eventually the opening and midgame strategy will be mapped out in more detail for the moment even basic strategy is not well-known. From the few games of it I played the other night with iwk, it appears that (1) the temptation (bad or good, I don’t know) is to call out the small pieces first, of course; (2) calling out very awkward pieces like I5, O4 or V5 at the right time is the real building-block of strategy.

Posted in blokus, variants | 1 Comment »

XF Tetris-Time packing

Posted by nand on February 21, 2010

By request, here’s the 1-point loss for orange for one key line of XF Tetris-Time. There are a few different possible packings in top right but the key is to use I3 and V3.

Moves: 1. X – X / 2. F – N / 3. N – V5 / 4. W – F / 5. T4 – L5 / 6. L4 …. and the rest is packing.

Posted in openings, XF Tetris-Time | Leave a Comment »

FW solution: more pieces to the puzzle

Posted by nand on January 8, 2010

OK, here’s a few more installments in my continuing battle against this opening. In my view Z5 is probably the strongest 3rd move for violet (now that I think I’ve dealt with Y-kiss). So here’s some lines that I think should do it for orange.

1. F – X / 2. W – N / 3. Z5 – F / 4. I5 – W / 5. X – Y / 6. U – L5.

…. 4. N – L5 / 5. X – Y / 6. U – P.

This is the trickiest line as orange has no combined block+attack on bottom. Here’s one possible line. I won’t spell out the moves as they follow the same pattern as above.

This is where I get uncertain. Suppose violet ignores orange F? What is orange’s best move on top? (If orange blocks the N with e.g. T4 then this is about a 4-point loss for orange IMO.) The game becomes very open, with orange having the smaller area but two leaks into violet’s area; violet has only one leak into orange’s. I THINK that this orange Y is probably the best move but would have to work it out in more detail. (The other obvious moves: turn the knob on the Y the other way; use Z4(G12rdr) for an unblockable move in anticipation of blocking on bottom right on the next turn. Probably others too.)

Posted in blokus, flawed openings, FW, openings | Tagged: | Leave a Comment »

Blokus wishes for the New Year

Posted by nand on December 17, 2009

I know that probably there’s little incentive for Mattel (the new owners of Blokus) to do a lot of tinkering with its site, since membership is free & thus there’s no monetary reason to hire a computer tech guy to make it run better… but a guy can’t help wishing, can he?

So here’s what I think would make it a better site.


  • A warning bell for when the timer drops below 1 minute. This would take, like, about 2 minutes of a programmer’s time to add… it’s unbelievable that despite this being frequently requested by players, this never gets added.
  • 3D Duo in the Competition room, not just in Training.
  • Add grid coordinates along the sides of the board–in duo: A through M on the X axis, 1 through 14 (bottom to top) on the Y. (This could be a toggle button: SHOW COORDINATES/HIDE COORDINATES.)
  • Add an option to number pieces according to the move they’re played on, so you can actually figure out the entire sequence of play at a glance at the board. (This could just be a toggle button: SHOW MOVES/HIDE MOVES.)
  • Install anti-spam software on the forum. I’ve never come across a more spam-prone online forum — it’s truly embarrassing. They eventually get around to cleaning it up by hand, but there are much better automated ways of ensuring this stuff never gets posted in the first place.


  • Add an option to permit players — within the Competition room — to choose sides rather than being assigned them randomly. This would obviously require BOTH players to consent (they would each have a button). This would save a lot of headache when players are trying to resume a match (currently, the only solution is to keep quitting & returning, hoping that the other player is not such a schmuck as to penalize).
  • Fix the poorly-conceived censorship in chat. (For now, let’s set aside the question of whether there should be censorship.) If it’s going to be done, at least program it competently. First: It should not be triggered by part-words. It’s dumb to turn words like “assuming” or “culminate” into “***uming” and “***minate”: if you want to guarantee that it catches both “fuck” and “fucking” then simply put BOTH words in the blacklist. Second: given that virtually all chat takes place in English, no words should be censored that are innocuous & commonplace in English: e.g. “pot”, “con” and “fan”.


  • The best solution to online misbehaviour would be to get rid of the censorship entirely & use a different system: give some trusted players “moderator” status, with the ability to silence unruly players or eject them if necessary.

Posted in misc | 6 Comments »

FY open (vertical): possible line of defence?

Posted by nand on December 17, 2009

This is one of those really tricky lines for both players. No idea which player to name it after–HRF likes it but I’m not sure if it’s his originally. I have not got a surefire defence against it but can usually make life difficult for violet. Here’s the start of one line I’m working on:

1. F – X / 2. Y – N / 3. T5 – P / 4. N ….. I vaguely recall that for move 3, violet L5 to close the centre (H8rrru) is bad, but it’s not obviously bad, so I’d better actually go & prove that another time…

Obvious next move for orange is Y or L5 (I think Y) off the X — haven’t decided what’s the best orientation yet. In general, it’s vitally important for orange to play through the hole the moment he gets the chance — it’s too soon this turn, but I would recommend it on the next turn no matter what. The trick is to avoid messing up the nice 1-2 leak off the top of orange P by letting violet block both leaks simultaneously.

Posted in FY open, openings | Tagged: | 1 Comment »

FW rethought: Kissing

Posted by nand on December 17, 2009

OK, so I’m trying to rethink my approach to this, in part because there are some good midlevel players who still insist on using it despite its evident weakness. (It can win big against low- or midlevel players, I’ll admit; I’m purely concerned with optimal play, though.) Anyway, the most formidable of the “kiss” variants is one where violet tries to use Y and then Z5 or (better) T5 to round the corner, killing off all orange’s useful corners in the bottom left. Here’s the start of my line against it:

Moves: 1. F – X / 2. W – N / 3. Y – F / 4. X – W. Note that it’s a good idea to hang on to Y as a last-ditch block in the midgame (I1uur), though if it becomes freed up then it’s a major threat on top (L14ddl).

If violet is so foolish as to play N on top rather than X then you get one of my favourite positions, eminently winnable for orange:

Moves: …. 4. N – Z4 / 5. T5 – I5. This is an elegant example of an unblockable leak, since the only block (V5[F14ddr]) produces a horrendous I2-T4-I3 series of holes. You can see the violet T5 “corner kill” in action here — not that it does him much good.

If violet plays T5 on move 4 (or Z5) it’s a different line, I still think bad for violet. Will unpack it later on…

Posted in flawed openings, FW, openings | 3 Comments »

XF Yasu, preliminary proposals

Posted by nand on December 17, 2009

Sorry for the nonposting here lately… I always tend to be a feast-or-famine blogger anyway, & it’s been a weird last few months with the new job. I’ve also been gradually thinking more about the game, though it’s hard to be too systematic. Gradually I’m learning that it’s really nearly impossible to “solve” ANY opening, even the weakest…. there are simply too many possibilities. I think there are 2 types of players — the ones who try to keep to the “known” & the ones who welcome the “unknown”. I wish I were more of the latter type of player — great instances would be Toutatis and Kolub68 (neither of whom seem to be on the site anymore, alas), & often Bobby_Bob too. Nowadays lerpyfirth (previously known for the repetitive use of the infamous XF Lerpyfirth opening) is of this type: to some extent it can be just a sign of someone bored with “the normal game” (or someone who specializes in 5-minute games), but it can also in the right hands be a powerful “ice-axe to break the frozen sea” of standard play.

But I’m not usually that type of player — I tend to stick to familiar openings & try to thoroughly understand them & judge them by optimal play. Anyway, it’s served me in good stead… as well as leading to a few disasters.

Anyway, I wanted to get back to the infamous FW opening, in part because I think my posting below is wrong. But in the meantime, I think I’ll start trying to put more useful info on this site.

So, XF Yasu. I’ve been thinking harder about this one lately. It’s a fave of mid-level players, but it’s rather weaker than XF Rubik in my view. Nonetheless, it can be tricky, & I have not come across an airtight orange response. Here are two of the more usual defence formations. In my view, these are flawed, but will — with good play, which I’ll try to flesh out in future posts — get you a close game or a win versus anything less than top-notch violet play.

Orange has an unblockable left side, and is threatening I5(D7u) on left or some variety of block on the right (usually T5 or L5 — I’ll let you figure out the orientation). I usually use this one — despite its flaws — simply because newbies and even midlevel players have no idea how to handle it as violet.

This may be better, though:

This gives you the option of I5, I4, N or something else on the left, depending on what violet plays on the right (assuming he DOES play on the right). I’m less familiar with this line & look forward to exploring it.

Posted in openings, XF Yasu | 1 Comment »