Duo to the Death

Blokus has taken over my life

Archive for the ‘openings’ Category

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 »

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.

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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 »

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 »

(rejected) FW: complete solution, part 1

Posted by nand on October 16, 2009

Considering all the depressing news I usually post about hard-to-beat openings, I thought it time to post something on an eminently defeatable opening. Sometimes I have a little trouble with it, so I thought it worth trying to work out a solution in more detail to avoid mistakes. As always in duo, even bad openings can win if you make a single error in your defence…

So: FW, the favourite of beginning & some mid-level players. It’s an interesting opening in that it looks pretty good but is actually one of the flimsiest of the F openings. I think this can actually be defeated by orange in ALL cases, though I must confess that I haven’t (inevitably) worked it all out. I would be very interested to hear from people who have suggestions for lines I should examine in more detail.


UPDATE: I’m no longer happy with the line given below, as I think violet has a strong reply to the orange Z5. I will try to post more shortly. I will keep this page here nonetheless as an interesting false start.


Here’s the basic orange response:

FW basic opening

Violet must reply on the left. (If violet plays on the right, orange plays I5(D7u) and the game is easy: I won’t spell out that line here as it should only require basic understanding of duo strategy.) There are basically two possible replies: a hang or a kiss. My solution is simple: if it’s a hang, play Z5(K8ullu); if it’s a kiss, play F(K8uul). I’ll consider the various cases in turn.

Case 1a) Hang and circle

The usual pieces for the violet hang are Z5(E7lddl), T5(E7ldd) or N5(D9ddld or dldd). If violet circles, orange should keep going aggressively rather than block until violet pokes up around the side. Here’s the line:

FW with a Z hang, the circling game

Note that orange F grabs the V in the nook of the violet F (& note that orange Z4 is dependent on keeping the W for a block). This game should produce an orange win of about 3 points. If violet plays T5 not Z5 then orange needs a different path, playing W(A8urur) to grab the L4 spot in the nook and using a different blocking method on the right (you figure it out).

If it’s an N hang, then it’s a little trickier, but the I5 is still the best bet, I think. At worst it’s a tie but here’s my packing for a 3-point win:

FW with N hang, orange I5

Moves: 1. F – X / 2. W – N / 3. N – Z5 / 4. Z5 – I5 / 5. I5 – T5 / 6. T5 – F (very important to tee up the I3!) / 7. L5 and the rest is hole-filling and packing.

Or if you like to make things exciting this is a good line too, & possibly a larger win (I haven’t worked it out in full but in practice it can lead to bigger wins versus players who aren’t good with open games):

FW with N hang, circling

Posted in flawed openings, FW, openings | Leave a Comment »

XF Lerpy du jour #2

Posted by nand on October 1, 2009

Another line I’m thinking about. The orange V5 is an experiment… actually it’s not bad, 4pts loss is respectable though I usually try in “solved” lines to get it down to 3 or under. In general I want to find the key points where orange can play a defensive move without resulting in a huge loss (this is useful for tournament play).

Lerpy 1 Oct 09 game C

Moves: 1. X – X / 2. F – Y / 3. T – N / 4. W – L5 / 5. L5 – I5 / 6. N – W / 7. Z5 – V5 / 8. U – T4 / 9. Y – L4 / 10. I1 – T5 and the rest is packing.

Note if violet plays L4 for U, then orange must not use the L4 to block (it’s needed on the right). Use O4 and I2 to block–one less point, but violet also gets one less point so the results are the same.

REFLECTION: Violet Y could also be V5 (the V3 leak doesn’t matter much since orange has already left a V3 spot for himself in top left corner). Then violet gets an extra I3 but (playing through the leak) orange also gets an I3 in bottom right & the results are identical.

Posted in openings, XF Lerpy | 4 Comments »

XF Lerpy du jour #1

Posted by nand on October 1, 2009

Still thinking a lot about this opening recently — I haven’t posted much on it lately simply because I want to give genuinely useful responses (otherwise this risks simply becoming a how-to manual for people looking to win as violet by lifting games from the blog… it happens). Anyway, my suspicion is that versus good violet play it’s hard to do better than a 3-pt loss. But it’s so complex I won’t pass judgment until a lot of lines are explored.

Anyway, for the moment I’m primarily interested in what is in my view the best reply: orange Y with the knob down. So I’ll just start regularly posting games that I think are close to optimal play. If you have suggestions for where orange or violet went wrong, please post comments, as I want to really map this line out.

OK: so this line is the result of some discussion with oldmanc, who agrees with me that the orange N kissing violet F on move 3 is kinda weak. We have both toyed every so often with L5 in that spot instead. I think these games show this may be promising.

Lerpy 1 Oct 09 game A


1. X – X / 2. F – Y / 3. N – L5 / 4. Y – Z5 / 5. T5 – W / 6. L5 – I5 / 7. I5 – F / 8. Z4 – N / and the rest is packing.

This could be improved (the screenshot is from a live game): orange plays V5 in place of N, P in place of O4, N in place of P. One point more for orange!!! But violet can also improve on it: U and 1 in place of the P, and P in place of O4. So we’re back where we started, just 62-59.

Lerpy 1 Oct 09 game B

oldmanc thought violet might do better by blocking orange I5. This game suggests the results are more or less the same. It’s a little hard to tell because both sides have to worry about leaks so packing gets tricky.

1. X – X / 2. F – Y / 3. N – L5 / 4. Y – Z5 / 5. T5 – W / 6. L5 – I5 / 7. W – I4 / 8. I5 – P / and the rest is packing (but violet must not play the O4 till orange has used up the I2, otherwise there’s a leak).

Posted in openings, XF Lerpy | Tagged: | Leave a Comment »