COMMON GAME is a game where both sides have +- same number of ko threats with +- same value. Creating a three step unfavorable non-picnic ko is not good in a common game, although in some games it might be possible.
(;AB[rr]AB[rq]AB[sp]AB[ro]AB[rn]AB[sm]AB[qo]AB[pp]AW[rp]AW[qp]AW[qq]AW[pq]AW[oq]AW[nq]AW[mq]AW[lq]AW[pn]AW[ql]AW[rl]AW[sl]AB[op]AB[oo]AB[ol]AB[pk]AB[rk]AB[rj]AB[ri]AB[rh]AB[sk]AB[si]AB[sg]AB[rg]AB[oj]AB[nk]AB[ml]AB[nn]AB[mm]AW[qj]AW[qi]AW[qh]AW[ph]AW[oi]AW[og]AW[nh]AB[no]AB[mn]AB[nj]AB[qr]AB[pr]AB[or]AW[qs]AW[ps]AW[os]AW[ns]AB[rs]C[Common game: white to play]AW[nr]AB[qn]AW[pm]AB[qm]AW[pl]AB[pj]AW[pi]AW[ni]AB[nm]AP[goproblems]
(;W[po];B[qk]
(;W[rm];B[so]
(;W[sq];B[sr];W[sn]C[Ko, white takes first and black has to win it twice. Black also risks significantly larger group than white. Obviously very good in a common game.RIGHT])
(;W[sn];B[sq];W[sr];B[sm]C[Ko, black takes it first and black has to win it twice. Slightly worse than the solution.]))
(;W[so];B[om];W[sq]C[Black is okay with this result. The loss is not big and black has sente.])
(;W[sq];B[om];W[so]C[Black is okay with this result. The loss is not big and black has sente.]))
(;W[qk];B[po]C[White could do better.])
(;W[so];B[qk]
(;W[po];B[om];W[sq]C[Black is okay with this result. The loss is not big and black has sente.])
(;W[sq];B[po]C[White gained a few points in sente, but the gain is too small.])))