It's a good concept, but it's bare-bones and artificially difficult. There's no way to know amounts needed for upgrades, only which types are missing. It's weird to have a quota of materials you can't use without explanation. I'd assume survival, but it increases by much more than any one person needs to sleep for a night. First it's easy to make it through a day, but it quickly becomes annoying to defeat enemies because of the use of tiles. Enemies can attack and move diagonally, but I can't. It becomes a gimmick of artificial difficulty where I have to get hit in order to get close enough AND be in a direction I can attack from. That's not an actual challenge in any way, since some rooms have too many enemies to simply dodge. It's RNG after a while, honestly.