To the OP:
I know you were just throwing ideas out there for the sake of it, but just for a minute I’m going to pretend those were real game pitches. This isn’t addressed to you so much as it is to all the people I see on forums who post ideas like this and seem to think they can actually get someone to make them one day.
What I really noticed is that a lot of your ideas were basically just “take the blueprint of an existing game, but set it in the universe of a different existing IP”. You’re not alone in coming up with ideas like that, there are a couple that come up in Halo forums all the time. Whenever I see a thread title like “Hey, I have a great idea for a Halo game”, I can say with about 90% certainty that if I open the thread the idea will end up being either “Battlefield/Star Wars Battlefront, but Halo”, or “Mass Effect, but Halo”.
Seems like a cool enough idea, right? The game is cool, the IP is cool. Combining them is a can’t-miss idea, right?
It’s not quite that simple. I’ve likely already paid my money for the game you’re using as the blueprint for your game idea. If you want me to go to the store and hand over more money for your game, you need to explain to me why I should buy it even though I’ve already paid for a game just like it. In other words, how is your idea better than the existing game? In the case of the Halo examples I mentioned above, “Because it’s Halo” is a probably good enough reason for some people, but probably not for enough people. What can you sell me that I can’t already buy from someone else?
Take Halo Wars, for example. That game wasn’t really marketed as “Existing RTS, but Halo, so you should be excited”. The real message behind the marketing for that game was “We’re redefining the RTS genre to make it really work on a console. We’re making the game that will get that right in a way you’ve never seen before. And by the way it’s Halo. So you should be excited”. Whether or not they succeeded or not is up to you to decide, but that’s what they offered. And people were excited.
What I’m really saying is, you need develop your ideas so they become something people haven’t already played. It doesn’t have to be radically different. In fact, radically different game ideas can scare people away, since they’re not sure what to expect compared to a “safer” but less original option. You can still draw huge inspiration from other games. But it should be different enough to have its own identity as a game.
Why should I hand over my money? Why should I be excited?