First post and about to make my first foray into Unity engine. After weighting in all the various engine out there (I considering UE and XNA but decided on Unity due to my C# background in web development and the fact that XNA is not supported anymore).
My initial question was this.
For the Terreria game (Done in XNA) on PC/Linux/Mac, is their artwork procedurally generated? By this I mean are they creating all the graphics using code or are they using sprite based graphics?
http://www.aseprite.org/ is supposed to be a decent editor. Learning and doing that kind of art probably takes a lot longer than you think. I was surprised how hard and tedious it is when I tried it, and I have over 10 years of more traditional digital painting experience.
PyxelEdit is another good one. I bought that not only for myself but also the main artists I contracted pixel work out to just so they could give it a try. It’s cheap as I recall. Maybe $10 or so.