Currently you have to press 'Esc', then 'down' and 'Enter' if you want to restart a level. It doesn't take too much time, but I still think that it would be nice, if we had a hotkey, perhaps 'r' or something to quickly restart a level.

A sokoban-like game is literally unplayable without undo.

プレイヤーの周囲2方向に押せるコンテナがある状況で、 移動キー同時押しでコンテナを2つ同時に押す→zキーでアンドゥを行うと、 たまにアンドゥ時にコンテナの位置が正しく戻らない（マス目を跨る場所でコンテナが止まる）事を確認しております。...

Hello, I tried your game recently, the concept looks great ! But I would like to enjoy the game with the music only, as the sound effects irritate my ears. Best regards