Snake Pit

The board is a pit of snakes. The opening at the top stays empty — snakes cannot enter it. Extra empty squares let snakes slide, and let the ladder move left and right as well as up and down. Climb out through the top. Linger too long or spend too many moves, and a snake bites. Each board’s cutoff is the average finish for that board plus a tenth — we do not set the pace. Pick a board, then a level: each level is the same rules with a different starting layout. Later levels start the ladder farther from the opening and mix the snakes more. 3×3 has two levels of loose snakes. 4×4 has one two-square snake; the rest slide as singles. Level 1 sits that snake on the opening, so it has to move before the ladder can climb out. 5×5 has one 2×2 snake; the rest slide as singles. 6×6 has one 2×2 snake and one post that never moves; level 5 also adds a two-square snake that lies flat. 8×8 steps it up: one 2×2, a flat two-square snake, and two posts; level 5 also stands a two-square snake on end. Levels 6 to 10 keep two 2×2 snakes and two standing 1×2 snakes; a 2×2 sits on the escape and a 1×2 sits on the opening, so both must move before the ladder can climb out. Each level plants those pieces in a new spot and adds another post.