Hey!
Our survivors don’t have any attributes, so when a survivors gets a level up, the only consequence is that he can unlock a new skill (which can unlock new crafting recipes, increase the damage, speed up crafting/disassembling, etc.). As skills are deactivated in this demo, so basically there is no leveling at the moment.
Generally, there are no XP or anything like that – you get a level up each morning, after you survived a night.
Our initial idea was that you can level one of the survivors each morning, but maybe it would be a better idea to give a level-up to each survivor every morning.