LÖVE

What do you think about games being in forced 16x9? Also, would traditionally animated cartoon sprites over semi-realistic pre-rendered 3D backgrounds look really weird? I'm thinking about starting on a major project (private early on) with a little help from a friend of mine that may take months, and I don't want to mess up in the early stages.

Aspect ratio shouldn't be a problem as long as you make it reasonably small to fit most monitors. I'm thinking less than 1280x800. As for the art style, I can only say that it depends! If things mesh well together then it doesn't matter if it's cartoon + 3D. Remember that Donkey Kong Country was pre rendered and looked great.

EDIT: If you're going full screen, I'm sure most people will know how to set their scaler to maintain aspect ratios.

Write (and share!) a letterboxing library!

Might help folks on 4:3 who run a 16:9 game, and vice verse.