My goat Flappy Bird 3DS on Universal Updater.

If you own them, try the Sonic Mania/1/2 decompilations. (Mania only works on a new 3DS.) I'd also try out all the emulators, they're pretty great!

i'd recommend themes cuz they r cool. you can scan qr codes on themeplaza.art . also, if you have majora's mask 3D you should get project restoration. there are much more things though. hope i helped in any way! =D