I need help
What kind of a simple 2d game can I make on play canvas
My 2nd question does playcanvas use a modified JavaScript library
My 2nd question does playcanvas use a modified JavaScript library
Yes it is quite possible to make a 2d game in playcanvas, however the engine is primarily designed for 3d games and at the moment 2d tools are somewhat limited.
Depends what you mean by modified. The Playcanvas engine uses ES5 javascript which is pretty much standard across the web.
If you are looking for a simple game to make to learn, try making Pong, Space Invaders, Tetris, etc. They are good starting points. Pong especially if you have never made a complete game before.