Hi,
I was wondering if everyone could list off some limitations of platformers that use pxl-test for collision (I mean pixel-perfect collision, no tiles). That is what I am doing, and I want to know what is bad about it.

Here's some:
-Enemies cannot move off the screen or they will have no collision
-Takes up more storage than using tiles

Could everybody tell me more? And if possible, a solution to it?

it's typically slower than tile-based collision as well.

a possible solution would be to keep your map storage and drawing tile-based and then implement a pixel-testing system that looks for "pixels" within the tile data rather than on the actual buffer.

what i mean is that the character/enemy or whatever would first determine what tile is underneath it and then, rather than pixel testing on the screen buffer, would check pixels in the sprite that is used for that tile instead.

The only real way to have different types of pixels is to have a different image for each property.  The destructible image (often reffered to as a mask) would not be displayed, but instead used to test whether or not a pixel is destructible or not.  As you can imagine this can increase your file size by large amounts, which is why people generally use tilemaps.

Can you store color onto your images?

Then you are quite limited on how you define what type your pixels are.  You can either use the multiple image method, which gives you a good speed, or you could store the position and type of all the 'special' pixels, which is likely going to be space efficient, but also quite slow.

no, you would draw the images at all, they would just be used for determining the type of a pixel.

Oh can you only do pixel testing on the screen, not on images?  In that case the second method I suggested would be one of the only ways

do you have other free-ram areas you can store to, though? you could store your images there. it may mean writing your own pixle test routines, but should still be faster.