I love the game and I've played it for a long time and the game never gets old. I know the game is still in development so maybe you adding them already but what I suggest you should add to the game is a pause button when you playing as well as an endless mode where the game doesn't end after collecting the artifact but continues(so this can be a reward for completing the main game that appears when you get the artifact and it gives a choice between "x to be reborn" or "z to plunge deeper"). I would love these to be introduced to the game and I think it will make this great game even better and more fun.

edit:
came back to this game after a long while and just realized that being reborn carries over your powerups :/