Hi. I`m trying to make a 2D platform game using DirectDraw. The world rendering is done with the classic tile-based scrolling. Tiles properties and walkability have been defined and implemented, too. All done, till here. My model is Sonic the Hedgehog (who doesn`t know it..), but I noticed that it`s very complex and different from other tile-based games in many parts, parts that I just can`t figure out how to implement. Not in an easy and immediate way, I mean. - Fluctuating bridges - Walkable wheels - Rotating platforms - Angulated collisions - VERY irregular tiles - Maaaaaaaaaaaaaany many many many *MORE* ... I find a *lot* of Physics in many of these problems.. Furthermore, is it convenient to represent them as sprites I suppose, and not tiles. Is this a reasonable approach? Please help me to get a bit out of this confusion.