First of all, I have done some research on this topic before asking, and I'm asking this question as a mean to get some opinions on this topic, so I don't make a decision only on my own, but taking into account other people's experience as well.

I'm starting a 2D online RPG project. I am using SFML for graphics and input and I'm creating a basic game structure and all for the game, creating modules for each part of the game.

Well, let me get to the point I just wanted to give you guys some context.

I want to decide on how I'm going to work with collision detection. Well I'm kinda going to work on maps with a tile map divided in layers (as usual) and add an extra 2 layers - not exactly in the map - for objects. So I'll have collisions between objects and agents (players - npcs - monsters - spells etc) and agents and tiles. The seconds one can be easily solved the first one need a little bit of work.

I considered both creating a basic collision test engine using polygons and a quadtree to diminish tests since I'm going to be working with big maps with lots of objects - creating both a physical and graphical world representation. And I also considered using a physics engine like Box2D for collision tests.

I think the first approach would take more work on my part but the second one would have the overhead of using a whole physics engine for just collision detection and no physics.

What do you guys think ?