@eniko While I know of some games that have managed pretty good visuals in small screens (eg.: Monster Hunter on the 3DS, 224p), 1.- those use a vastly different visual art and engine, highly reliant on zoom and 2.- 100px is still too small for that, IMO.
At that size limitation and if you might be facing redoing all the art for porting to consoles anyway, have you considered switching the art style to "symbolic" and using "symbolic tiles" rather than "graphic tiles"?
Kinda like games such as #ZZT did back in the times of the DOS, when you had to deal with 80×25 terminals (no graphics mode, even).
Symbolic visual art can also give a game a pretty fresh coat of paint depending on the genre, as can be seen in games such as #VVVVVV , and on a console port you could even add a "retro option" switch for the visual engine like how #MonsterBoy does, for extra fancy.
For extra bonus, on symbolic tiles you could even just use fonts for some symbols, since many of them have a 10pt option.