I'm hosting a chess night and would like to post a few wallchart puzzles but would like to discourage folks from secretly whipping out their phone's chess app/engine and scoring points unfairly.
For example, something like this every-Russian-schoolboy-knows endgame breakthrough position here with white to move where removing the Kings renders the position invalid/illegal by most engines, yet still has enough context to give a person a visualization/calculation challenge if they've not seen it before.