Oh man I bought so many games based on box art, tv/film licenses I enjoyed/recognised, or based on nothing but hype from games magazines.
Notable examples:
- V-Rally for original Gameboy is complete crap, but the cover is super cool.
- Rainbow Six: Lone Wolf was cheap cash-grab to follow the success of the original Rainbow Six on PS1. It's a 5 or 6 level game with 1 character instead of 9, a single piece of music that only plays during menus, and eyestraining graphics. Absolutely awful, but SOMEHOW I was convinced it must have been tense and exciting based on nothing but the cover.
- Mortal Kombat V: Deadly Alliance for GC was hyped by the mag I read for months. Stupidly I bought into this for some reason, despite being awful at fighting games and disliking the art style clearly on display in the magazine haha.
EDIT: Conversely, if games have hideous icons in download stores, I tend to pass on them. Tekken Tag Tournament 2 comes to mind in particular here.