How tall should each slice be?
Choose how much of the previous player's work the next person sees. More reference = easier continuity. Less reference = more chaos. Your call.
50px reference, grid guides, top + bottom overlap. Good for first-timers.
30px bottom reference. The classic exquisite corpse experience.
Minimal reference. Souls fly blind. Results may vary wildly.
Classic mode. See the bottom edge of the previous slice.
See both edges. Better continuity, easier alignment.
Pure chaos. No reference at all. Good luck with that.
Overlay a subtle grid on the canvas to help with alignment. Handy for beginners.
Your canvas (no grid)
Bottom reference