How about a survival platform game. The game will include multiple different levels, and on each level you would have to survive a certain amount of days. In the levels you can get rewards and resources which you can use for future levels. The game would also get progressively harder, and you have to use the resources you had from previous levels to create structures and weapons. You could also have different tiers of weapons, and rarer materials create better weapons. On the levels you also would have to fight enemies which also may only spawn in night or day depending on the enemy.
That is my game idea for anyone to hopefully use!