Andrew Hussie is the writer and artist of the webcomic MS Paint Adventures, which updates prolifically. So far there have been four adventures: the unfinished stories Jailbreak and Bard Quest, the completed Problem Sleuth, and the ongoing Homestuck. Problem Sleuth has been fully collected, and Homestuck has begun to be compiled.
Thematically, the MS Paint Adventures series are meant to be similar to computer RPGs. 'Commands', found below the panel, are used to go from one page to the next. The characters react accordingly (though the only story with real differentiations due to 'command' choices was the brief Bard Quest). This was especially true of Problem Sleuth, the main theme of which was a mockery of the aforementioned RPGs.
Despite the title of his site, MS Paint Adventures is actually made with photoshop, allowing for Hussie's signature style. However man people still mistakenly think he uses MS Paint.
Andrew Hussie likes messing with his readers, and frequently breaks the fourth wall with self-inserts, typically during moments of major drama in the story.