Sometime in the mid-2000s I imported a flash cart for my Game Boy Advance. Not for piracy, of course, but for the wealth of homebrew games and apps developed by amateur coders around the globe. It cost about $60 and held a whopping 32 megabytes. But I had an NES emulator in the palm of my hands, so that was cool enough for me.
These are some of my favorite apps from the time.
But hey! You may be surprised to hear that GBA development is still going fairly strong today! For ROMs and news, I'd recomment checking out GBAdev and PDRoms. This is all freely distributed software, so explore to your heart's content!
It's Tetris with a twist! Try clearing lines as the entire board twists, tilts, sizzles, and smears itself across the screen. There are a handful of modes and some unique mechanics I'm not sure about. Also be sure to check out the alternate backgrounds in the pause menu.
Honestly, this was probably my favorite GBA homebrew game for the time. Play it if you like to barf.
Also I think the Tetris Company might've sent a cease & desist over this game. So that's pretty cool. Thanks, Tetris Company.
Bullet hell on the GBA? It's more likely than you think! This game includes four levels of wave-based boss attack against a central core. The white bullets can be cleared with your shots, but this turns them into troublesome homing pink and blue bullets. This constant pressure keeps your ship on the move. Extremely difficult! But cool.
A pseudo-followup to Vulkanon. As you can tell by the screenshots, this game uses a vertical orientation that asks you to flip your GBA. It may be awkward to play on an SP, but try playing it on a Micro!
Similar to the previous game, this one includes four levels facing off against a stationary core. There's no tricky bullet clearing here, just simple pattern dodging. The screen-clearing bomb has been replaced with the limited ability to slow time.
On top of that, there's also the "barrage selection", which seems to include a vast number of bullet patterns from various games such as Dodonpachi, Touhou, Xevious, and others. I suppose you could consider it a "training tool" of sorts.
A Game Boy style shoot-em-up in the vein of more "realistic" affairs like 1942 or Tiger-Heli. It includes three stages, and any of that realism goes immediately out the window with the... surprising final stage. I think a colorized version was in the works for a brief period, but never got finished. The source code is available though, so maybe you can make your own.
A Zelda-esque action/adventure game, and a fairly sizeable one at that. There are five dungeons and a full overworld littered with secrets. You could easily sink a few hours into this one.
Super Star Shooter was a doujin shmup created by The Dotmap Brothers (no relation) for the Sharp X68000 in 1991. It looks and plays very similarly to Star Soldier. A "caravan" shooter, the game challenges you to get the highest score possible within 2 minutes. It can get pretty addicting.
A Wii port was also created years later, and even an iOS version called Super Star Shooter Gaiden.
A very solid adaptation of the classic arcade puzzler, especially for 2002. Includes "normal" and "widescreen" modes, and even 2-player over link. This was another favorite of mine.
Sonic the Hedgehog GBA
by Stealth (2007~2008)
Sonic the Hedgehog Genesis was an infamously terrible and broken port of Sonic's debut game to the GBA. This fan-made proof-of-concept was created to show that an accurate adaptation was totally possible.
This demo includes the entirety of Green Hill, the special stage, and a partially complete Labyrinth Zone. And it also includes playable Knuckles and Tails.
Stealth would later go on to co-develop the well-regarded official mobile ports of Sonic 1/2/CD, and later still the prestigeous Sonic Mania. You could say Sega learned something. Maybe.
Probably the most famous and well-supported emulator on GBA, PocketNES was personally a major draw towards getting a flash cart for me. I was sorta obsessed with the NES, and in the mid-2000s, having NES emulation in the palm of your hands was pretty novel. (Plus it paired nicely with my NES edition GBA SP.)
Compatibility isn't perfect, but it's still extremely high. Punch-Out, as a famous example, has very corrupted graphics. Audio also might not sound exactly how you're used to. But the vast majority of games are 100% playable.
There are a number of scaling options to compensate for the GBA's lower screen resolution. There's support for save states, cheats, and even single-cart multiplayer if the game is small enough.
PocketNES was actually released as public domain software. As such, it ended up used in a number of official commercial releases -- specifically, some Japan-exclusive compilations from Hudson, Jaleco, and Atlus. (It's also commonly found on pirate carts, but hey, that was always gonna happen anyway.)
A Game Boy and Game Boy Color emulator. It was initially spun-off from Goomba, which only covered monochrome GB games. Runs pretty much flawlessly. Also supports Super Game Boy borders and palettes.
A Game Gear and Master System emulator. Also has near-perfect compatibility.
The SMS doesn't have the vertical resolution of the NES, so the screen squashing here isn't so bad. But there's also a nifty feature for unscaled mode that can (potentially) keep a game's HUD window visible no matter where you raise or lower the viewport! And on the GG side, you can disable the border to (potentially) increase the screen real estate, which can actually work quite well depending on the game.