I'm part of a small team that wants to make a game together. I have a little experience with GameMaker, but we want to make something more complex. We have an idea of a 2D action adventure game kind of like Zelda; top-down, sword swinging, item collection, some rpg elements. We are computer science majors with programming experience (mostly Java, C++, and C), so we don't mind getting our hands dirty in the code. Though some of us are artistically inclined, no one's really an artist so we'd prefer something that provides a lot of graphics help. Does anyone know of a 2D engine we could use as a sort of springboard towards making a more professional quality game?

Alternatively, if it would be better for us to start everything from scratch (programming the engine ourselves, getting some dedicated artists on the team, etc.), do you have any general suggestions?

So I could use, say, Unreal Engine 3 to make a 2D game? ...Oh, well duh, I guess they did use Unreal to make Shadow Complex. I need practice using more professional tools, so I may use Unreal instead of RPGMaker.

I know of XNA, but not much about it. What is the difference between a framework and an engine?

RPGMaker, GameMaker, Unity3D, and their ilk give you a complete tool chain (such as map editors, sprite editors, commonly used logic and entities built-in) that allow rapid development. The downside is that you are locked into using what they provide for the most part. Straying too far outside their intended domain makes development harder and in some cases impossible.

Using something like SDL, DirectX, XNA gives you more liberty, within time and hardware constraints - but you need to produce the tools & logic yourself, or find 3rd party tools and libraries yourself. Expect much longer development times, even for those with experience.

Generally, the more domain-specific a framework/engine/library/language is, the easier it is to get something done with it.

There are other questions you can ask yourself to help decide:
* Am I doing this as an exercise to learn some particular aspect of programming or design?
* Do I want to get something done as quickly as possible?
* What hardware/systems am I targeting?

Without knowing anything else, my 2cents is to "graduate" from GameMaker to Unity3D. I suggest this because I have some limited experience with it, and it basically gives you anything you could want for developing a game, even a 2d game like you describe. Scripting is done in C# (or javascript). There is a definitely a learning curve using it, but I suspect that someone familiar with the tools could produce something like what you are describing fairly quickly - it's conceivable that the content would take longer to produce in such a project.

Good luck!