@Felthry Mostly DS? I can help you with that.
Retro Game Challenge -- This is a very weird and charming game. You're sent back in time and forced to become a child living through video game culture of the 80s. It includes new games in a retro style and snippets of video game magazines to really give you this weird feeling of immersion in its world.
@Felthry
Ghost Trick -- It's a murder mystery, and you play as a time-travelling ghost who can possess and manipulate inanimate objects, and you basically use your powers to undo murders while trying to solve the mystery of your own death.
@Griff I think we've heard of that one, actually...
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@Felthry There are three Ace Attorney games and four Professor Layton games on DS, and I think all of them are worthwhile.
@Griff We've played the Ace Attorney series, but only some of the Professor Layton series.
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@Felthry Wario Ware DIY -- Your mileage may vary, especially now that there's no online community to back it up, but I found this to be a really interesting game-making toy. Very simple but surprisingly powerful.
@Felthry I'm hoping you've tried Elite Beat Agents. Very cute story-based rhythm game.
Most of the rest of my favorite DS games are either... you've probably already heard of them, or they were good for their time but may not have aged well.
@Griff we've heard of it but never tried it because we're really picky about music
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@Felthry For DS, my top picks are the Castlevanias, Lunar Knights, Phantasy Star Zero, SaGa 3 remake fan translation, Solatorobo
@Facet Phantasy Star Zero wasn't on the list, thank you!
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@Felthry It's not like, amazing, but it's pretty good if you wanted something with the general feel of classic PSO, but with cleaner/more updated movement and controls and general capabilities. It's not like the PSU engine if you're familiar with that.
@Felthry @Griff @Facet I mostly use my 3DS to play 3DS games, can't really help you there