http://commons.wikimedia.org/wiki/Commons:Licensing

broken name due to #

try opengameart.org/sites/default/files/pillars_%2302.7z (copy-paste to your addressbar)

Example:

a general collision detection routine defined in the engine code

engine -> function physics.detect_collision(object a, object b) ... end

calling engine collision routine for instances of objects created by the game code

game -> object a,b; foo=physics.detect_collision(a,b)

Defining a collision detection routine for the specific case of two players in the game code

game -> function game.detect_player_collision(player a, player b) physics.detect_collision(a,b) end

Also, if you can, place all the engine related code into the binary(.exe) and all the game/ui related code into dynamic link libraries(.dll/.so).

But these are if you want some flexibility and modification capability.

It is quite possible to meld everything(game engine ui etc) together which works quite well for small games.

You need to do the correct operation at the correct time