I have no idea. What type of 2d game would you like to play ?
Personally I think you should make a game that YOU want to play. That is the reason I, and many more (as far as I have noticed) make games.
However if you want some input:
- 2d platformers Terraria style
- 2d top down view dungeon crawlers
Those are the types of games I like to play when they are made very well.
Good luck and happy coding!
This isn’t really something we can answer. It’s a bit like an artist saying “what type of art should I make?” or a chef asking “what type of food should I cook?”
It depends entirely on YOU, your personal preferences, your experience, what you think is interesting to program and play.
Start small. Explore a mechanic you think is interesting. Go from there.
If you can’t think of a mechanic that you think is interesting, then start with a smaller game- make Pong. Then make it more interesting. Can you make Pong a 4 player game? Can you make a turn-based Pong game? Can you add lots of explosions to Pong? Those are just examples, choose whatever game you want and then spruce it up.
If it’s your first game, I would say begin small like KevinWorkman said. You will only get disappointed if you think of something big in the start. I personally started with a space shooter then a top down game and then a side scrolling platformer.