It seems the majority of people here don't know how to play a .gba (gen3) file, you need an emulator, https://mgba.io/ works for me, it can also run .gb or .gbc games, ie gen 1-2. Recommend this for rom hacks, and these links for gen 1, gen 2, and gen 3. Congrats, you can now emulator and download games you only legally own, *wink* *wink* and play them.