My first idea was asteroids but in first person, it that case it would be a first person shooter but in style of s Shmup. The game would be a remake on the classic asteroids with a twist of it being in first person which would give you the affect of having to figure out how fight off asteroids while not being able to see all of them. It a way it would be like VR asteroids, you only have control of you ship but other than that you don’t have a lot of sense where they are coming from until they are in a close proximity. All the rules stay the same, except for the first person part, and you would still need to defend yourself from the asteroid that are coming at you with minimum visibility.
My second idea was to have a shmup that has in-closing wall boundaries, as you progress in the game the walls get closer and closer. Its would be in a way a survival game mixed with shmup, you would have to survive the in-closing walls and enemy’s attacking you. There would be some sort of mechanic to keep the walls from closing in too fast or it could become a multiplayer where you have to hit a target to in-close the other players walls. The challenge would be to stop the walls or make it through the entire level without letting the walls kill you. If it becomes a multiplayer game there would be a serious challenge with having both enemies attacking and another player attacking as well. But it sounds like an interesting idea to pursue, it combines map obstacles and enemy obstacles to create a new shmup.
My third idea was a change of character, the playable characters would be watermelons with a elemental powers. Each melon has an ability that will help it on its journey through space fighting off enemies. Each elemelon has the ability of an element and you can filter through the different characters depending on the enemy you are fighting. The screen would be moving to the right at a constant speed so that the player doesn’t have an advantage to moving back, it has a mechanic similar to Cuphead. Its a constant fight with enemies or space junk, as you try to move from level to level. This is a space shoot em up game, that could become multiplayer possibly. But the game in its self would be a fast paste game trying to battle small enemies and Bosses.