I'm looking to create a game framework for my own personal use... I want to use WPF, but I'm unsure if that is a wise choice...

The games I will be writing should not require high performance graphics, so I am hoping to build on native classes... I do not want to rely on external DLL's unless I generate them myself.

The games will be for young children, say 4 to 8. Most will be learning puzzles or simple shooters.

The most advanced will be a platform game (non-scrolling screen like the old Atari Miner 2049er game).

I think I know how to write something like the old Atari Chopper Command (partially written and my 4 year old loves it, but I used WinForms and GDI), Pac-Man, Tetris, Astroids, Space Invaders, Slider Puzzle, but I do not really know how to write the platform game... In my mind, I'm getting caught in collision detection and how to make a character jump and how to make a character walk up a slope or steps...

Can anyone point me to information on developing a platform game in C#?

Would you suggest WinForms or WPF for game development?

I'm not looking for great graphics and speed, just entertaining game play...