Hey! Thanks for playing and reaching out. Apologies for certain aspects/features of the game being so opaque haha. The Select menu is our 'Level Up' menu. When you level up in the game, you receive a random boon/buff from that list. The select menu helps you keep track of which boons you have gotten so far in your run, so each time you level up, it will mark one off with an X. And, yes it is a rogue like, so each time you die, you start off again in a new randomly generated dungeon. You'll notice there is no save feature, so you just try to get as far as you can each run, until you face off with the Citadel's final boss. We're glad to hear that your enjoying the game, good luck Gnargoth!