I hate to over-post this shit but it *is* my recommendation for most of these threads:

Take a look at Stars Without Number.
>profoundly advanced lost-tech
>support for any setting from neolithic to post-scarcity (the TL column in this table stands for Tech Level)
>skill system stolen from Traveller
>only three classes
>the psionic class is neat and does not resemble the wizard shit you're girding to put up with

and if doesn't work, the same author is releasing Ashes Without Number (hardscrabble apoc) sometime in the next few months.