you can't save in this game,but once you've finished a floor you can press the button next to the elevator, leading to the next floor, which will ''save'' your game, but this is only exists for you if you wish to continue your run later. it is essentially a pause button incase you need to take a break from the game for whatever reason. however it doesn't actually save the game. if you continue your run after you've ''saved'' you will spawn on the next level but once you die you will still have to restart.

also, as a little sidenote, if you have anything unlocked while playing it will stay unlocked for future playthroughs. if you unlock an item from, for example, killing a boss, this item will continue to appear in future runs.

okay, thanks.

there is a button right next to the elevator to the next floor that let's you save and quit