I made this nifty problem after exploring after-game variations. Most of the time, I'm against player set-up problems (The type that requires you to play some moves set by the problem maker) since most of the time, they're unnecessary. But for this problem, I feel you can't fully appreciate Black's mistake unless you see it played out for yourself.
(;C[Please play on the triangle.]AW[cr]AW[dr]AB[cq]AB[dq]AB[er]AB[fs]AB[fq]AB[gr]AB[hr]AB[hq]AB[ir]AB[hp]AB[fo]AB[go]AB[io]AB[in]AB[hn]AB[ip]AW[iq]AW[jr]AW[jq]AW[jp]AW[gn]AW[fn]AW[en]AW[dm]AW[cp]AW[dp]AW[ep]AW[eq]AW[gp]AW[fp]AW[el]AW[ek]AB[gm]AB[fm]AB[fl]AB[il]AB[im]AB[jm]AW[hm]AW[hl]AB[hk]AB[jk]AB[ds]TR[cs]AP[goproblems];W[cs];B[bq]TR[es];W[es];B[fr]C[White to respond]
(;W[br]C[These black stones are doomed.RIGHT]MA[bq]MA[cq]MA[dq])
(;W[bp];B[br];W[bs];B[ds]C[The ko has become completely one-sided, there is no way that black can lose here.])
(;W[bs];B[br];W[bp];B[ds]C[The ko has become completely one-sided, there is no way that black can lose here.])
(;W[ar];B[br];W[bs];B[ds]C[The ko has become completely one-sided, there is no way that black can lose here.])
(;W[ds];B[br])
(;W[aq]C[Sorry, black won't be tricked here.];B[br];W[bs];B[ds]C[The ko has become completely one-sided, there is no way that black can lose here.]))