In this game, the beginner I've been tutoring, luft, almost brought down an intermediate player.
The first 4 moves look good, but then the intermediate player makes a weak move. With 5.L13, White creates a strong connection to the top, but the bottom of the board is still very open. A better move would have been, for example, 5.g14, which threatens to sneak by Black's i9 peg on the left (g9), or connect to the o10 peg, while forcing Black's blocks to either be too far to the left (for example, 6.h18, followed by a fight to the lower right) or too far to the right (for example, 6.i18, followed by 7.g18).
Anyway, my student took full advantage of White's timid move. (Good job, luft!) I think |6.L15 would have been even better, because it would force White to block higher, and White's problem is getting to the bottom. Anyway, |6.L17 is good, too. And instead of blocking it, White makes another timid move, 7.k15. Here I'd recommend 8.j16, for the same reason as above - forcing White to block higher. But 8.j18 is a winning move, too.
Anyway, Black tries to go around 9.t14 to the north, but leaves too much gap to his o14 peg. A couple moves later, 12.u13 is wasted, neutralized by 13.u12. Black then feels out the path over the top - there's nothing there. It turns out to be harmless (not affecting the overall board position), but it was worth doing just in case White screwed up.
So, back to the south option: 18.s18 was the obvious move, as I mentioned above, but potentially tricky. Inexplicably, White makes another timid move; it's like he doesn't want to reach the bottom. 20.q19 would have shut him down quickly - that's a 2-5 gap with L17, and both are linked pegs. But Black finds a way, anyway (there are many), so by 28.v17 Black has a commanding position. White's only hope is to trick Black in a run around the left side.
30.i16 may seem a little timid at first, but with i9 downstream, it's probably fine. Anything else risks a gap that could help White make a threat with his k15 peg. White needs a bold move now, but goes with 31.f16 instead. Black presses him further against the left edge with 32.h14. It really should be Game Over now. I don't see anything White can do.
Instead, Black played |34.e10, which is still a winning move, but unnecessarily leaves a tricky gap with h14. White makes the Triangle with 35.f12 (f16-c13-f12; each side of the triangle is one of the 3 major setups) which is hard to push thru, and opens up a potential threat of connecting to k15 or L13. Still, Black can shut it all down with 36.h11, but that is not obvious. White has accomplished an elusive endgame trick: while losing, lead your opponent into a situation where all winning replies are not obvious, and all obvious replies are losing in non-obvious ways!
After 36.f13, it looks very bad for Black. At first, I thought this was a losing position, but now I'm not so sure:
The first 4 moves look good, but then the intermediate player makes a weak move. With 5.L13, White creates a strong connection to the top, but the bottom of the board is still very open. A better move would have been, for example, 5.g14, which threatens to sneak by Black's i9 peg on the left (g9), or connect to the o10 peg, while forcing Black's blocks to either be too far to the left (for example, 6.h18, followed by a fight to the lower right) or too far to the right (for example, 6.i18, followed by 7.g18).
Anyway, my student took full advantage of White's timid move. (Good job, luft!) I think |6.L15 would have been even better, because it would force White to block higher, and White's problem is getting to the bottom. Anyway, |6.L17 is good, too. And instead of blocking it, White makes another timid move, 7.k15. Here I'd recommend 8.j16, for the same reason as above - forcing White to block higher. But 8.j18 is a winning move, too.
9.t14. White is getting desperate. He has to go around the right side or the left. He tries the right side first. This is Black's stronger side, so it's really BS. Hammer attack: 10.s14 11.r15 12.q15 13.p16 14.t12. Or, 10.s11 11.q11 12.q15. Or, 10.s17 11.o16 12.n16 13.q17 14.q13. The more obvious reply 10.s18 turns out to be a little tricky: 11.q17 12.p19 13.p18 14.???
Anyway, Black tries to go around 9.t14 to the north, but leaves too much gap to his o14 peg. A couple moves later, 12.u13 is wasted, neutralized by 13.u12. Black then feels out the path over the top - there's nothing there. It turns out to be harmless (not affecting the overall board position), but it was worth doing just in case White screwed up.
So, back to the south option: 18.s18 was the obvious move, as I mentioned above, but potentially tricky. Inexplicably, White makes another timid move; it's like he doesn't want to reach the bottom. 20.q19 would have shut him down quickly - that's a 2-5 gap with L17, and both are linked pegs. But Black finds a way, anyway (there are many), so by 28.v17 Black has a commanding position. White's only hope is to trick Black in a run around the left side.
30.i16 may seem a little timid at first, but with i9 downstream, it's probably fine. Anything else risks a gap that could help White make a threat with his k15 peg. White needs a bold move now, but goes with 31.f16 instead. Black presses him further against the left edge with 32.h14. It really should be Game Over now. I don't see anything White can do.
33.c13 is BS. 34.e11 35.e12 36.f13 37.d10 38.d9 39.c8 40.c7 should have put it away.
33.d11 34.e11 35.f12 36.g12 37.c9 38.e13 39.c14 40.b14
33.f13 34.f11 35.g11 36.f15 37.e14 38.e13 (the Puzzle 12 pattern)
33.f12 34.g12
... and that's not even taking advantage of the i9 peg. It really looks good for my student!
Instead, Black played |34.e10, which is still a winning move, but unnecessarily leaves a tricky gap with h14. White makes the Triangle with 35.f12 (f16-c13-f12; each side of the triangle is one of the 3 major setups) which is hard to push thru, and opens up a potential threat of connecting to k15 or L13. Still, Black can shut it all down with 36.h11, but that is not obvious. White has accomplished an elusive endgame trick: while losing, lead your opponent into a situation where all winning replies are not obvious, and all obvious replies are losing in non-obvious ways!
After 36.f13, it looks very bad for Black. At first, I thought this was a losing position, but now I'm not so sure:
37.d11 38.g9 39.h11 40.j12 41.i12 42.l11 and maybe it's still slightly in Black's favor after all?
After the actual 38.g11 39.e9 exchange, Black was doomed.
40.e5 41.f7 42.g6 43.h6 44.i5 45.j5 46.j3 47.l4
40.f7 might have had the best chance of tricking White, but it still doesn't work: 41.d6 42.e6 43.e8 44.d4 45.g7 46.g5 47.h5 48.i4 49.k4.