Here's a list of problems based on Nim (with their current difficulty rating):

301 Nim 15%

310 Nim Square 40%

409 Nim Extreme 55%

488 Unbalanced Nim 80%

509 Divisor Nim 45%

560 Coprime Nim 75%

629 Scatterstone Nim 55%

649 Low-Prime Chessboard Nim 30%

665 Proportionate Nim 50%

692 Siegbert and Jo

Sometimes I find I can solve related problems in quick succession. If you are the same perhaps this list might help.

Let me know if any are missing.

## Nim Problems

### Re: Nim Problems

If you search on "Stone Game" you'll find a few more Nim-style games:

260 Stone Game 70%

325 Stone Game II 80%

366 Stone Game III 40%

550 Divisor Game 55%

There are many others which turn out to be impartial games using Sprague-Grundy, but I won't point those out since it's not always as obvious that's what's going on, as it is for these stone/Nim games.

Like you, I got hooked on solving these in succession. Last April, I saw I only had 366, 509, 550, and 560 left from "stone game", and worked my way through all 4 in a 24 hour period. When I came up for air, I searched on "Nim" and found I hadn't solved 409 and 488 yet, which was disappointing. I did solve those, but months later.

260 Stone Game 70%

325 Stone Game II 80%

366 Stone Game III 40%

550 Divisor Game 55%

There are many others which turn out to be impartial games using Sprague-Grundy, but I won't point those out since it's not always as obvious that's what's going on, as it is for these stone/Nim games.

Like you, I got hooked on solving these in succession. Last April, I saw I only had 366, 509, 550, and 560 left from "stone game", and worked my way through all 4 in a 24 hour period. When I came up for air, I searched on "Nim" and found I hadn't solved 409 and 488 yet, which was disappointing. I did solve those, but months later.