While developing a small game using tile-mapping method a question came to my mind:

I would develop the game on Windows but wouldn't exclude adapting it to another platform.

What size(in pixels) would you recommend using for creating the tiles of a tile-mapped game(ie: RPG) with the following requirements?

• Have an acceptable level of detail without having too many tiles.
• Having a decent map size.
• Allow adaptation of the game on a handheld(ie: PSP), smartphone or a computer without too much loss of detail or slowdowns.
• Allow more or less important zoom-in / zoom-out.
• Have a resolution of tile that permits either pixel-perfect collision or block-collision.

Anything from a good explanation to a game example is useful as long as it can fit the requirements.

This question may seem a bit simplistic, but I noticed that many Indies game developer were using inappropriate scales scenery.

Also sorry for the poor syntax and the lack of vocabulary of my question, being a non-native English speaker doesn't help when talking about computers programming.