Thanks for hosting this giveaway, I definitely appreciate the opportunity to finally get an event legendary. Since I got my 3DS (for a good prize) in asia, I couldn't really get any codes here in Germany^^.
I haven't tried out many DS games besides Pokemon, partially because of the region lock, so I'd like to talk about a PC game that was quite influential for me:
Teeworlds. Basically, it's a multiplayer shooter game in a very simple 2D look, which has the premise of stealing the opponents flag and bringing it back to your own base. In order to do this, you are given an arsenal of weapons to respawn approaching opponents in their own base, and a hook to swing around for advanced mobility. Although the graphics might seem very simple, the game includes a great amount of skill and strategie, since you are playing in real time against other players. Teeworlds was in fact the first multiplayer online game that I came across, namely during informatics lessons in school when a few classmates realized that the wireless LAN connection between the computers could be also used for multiplayer games. As a bonus, you are able to redesign almost anything in the game, from your skin design to the maps you play in, and even create new mods of play if you're accustumed to CC+. In fact, I created a few game maps back than, which people still like to play nowadays.