For [way too long] now, I've been working on solving a customized minesweeper (classic) game that's as far beyond expert in mine density than expert (5/24) is beyond intermediate (5/32). So, in a maximum field of 720, 5/16 = 225 mines. Over the last several years, I have discovered how difficult this is (while learning quite a number of solving tricks), so I've ratcheted down the density a little. 210 mines? Solved a while back. 215 mines? Just solved, with hella luck. 220 mines? I'm taking a break. Maybe I'll start it back up next year, maybe not.