Anyway, I'm sure a consistent majority of you shmuppers has avoided GTA - San Andreas like plague. It's too obvious that for the stereotype hardcore otaku this western game sucks big: it's 3D, bad controls, bad framerate and, worst crime of all, it actually sells by millions and pleases the masses.
If that isn't enough, I can take out another group of people that have morality issues with the game, being filled with sex, violence, profanations of sorts, bad language and such.
However, for the two people that after reading "GTA" above continued to read, I'm here to share my passion for Los Santos' arcade games. They just rock!
Let's see what I found so far:
-They Crawled from Uranus-
A rather good Gyruss clone! it has warping, bonus points for clearing an enemy swarm, and weapon powerups. CJ even has an "arcade perfect" port of this classic at home in his cd-based console (at least it's shaped like acd-based system).
-Go Go Space Monkey-
This is the wacked Gradius fake. Space themed hori, only you're a space monkey. Successfully destroy an enemy line and you get a powerup (that floats on the screen in a very Project-X-esque fashion): these grant you rapid fire, spread shot and three way, after which you're basically invincible. The enemies become faster and faster, and sometimes avoid their bullets gets hard.
-Duality-
This has to be witnessed, I'm serious. This game is the most clever Ikaruga parody I've ever seen. It's basically an Asteroids clone, but you immediately realize from the title screen Rockstar is paying homage/laughing at Ikaruga. The screen is filled by big and small types of spheres, that can be either black or white. Big Black spheres will act as black holes, or planets if you want, attracting your ship with gravity and damaging you by contact. Big White spheres, just the opposite, will repel you. You can however destroy these Big spheres with your shot. The small spheres instead are "bonus pills" to pick up that replenish your fuel.
The best part is that Duality comes with two separate hiscores charts, a "white" one and a "black" one. Picking up white pills will increase your white score while lowering your black score and viceversa. So going for a white highscore means you'll have to avoid black pills and try not shooting the Big White spheres (you'd suffer from a penalty for shooting white), while destroying Big black ones.
Going for a black score is harder, since you'll be penalized for destroying Big Black spheres, and those are the only element on screen that damages your ship. However, each time you shoot your white score decreases by one, while shooting doesn't affect black score. So you won't have to worry for shooting too much.
If the whole thing seems intricate, boring and pretty far from the standard shmup blast-o-rama action... Well, that's a proof that DMA captured Ikaruga's spirit quite well, imho

I tried to sum Duality the best I could, but you can find even a FAQ for it on GameFAQs' GTA:SA page.
-Honey Bee-
Not a shmup, but still a lovely game in which you control a bee that must collect flowers and avoid thorns... Very cute! ^_^
Oh, I almost forgot: all these games can be played by both analog stick or digital pad. Very nice from Rockstar to implement that, although controls for Uranus and Space Monkey are a bit questionable... I wouldn't exclude however that too was made on purpose. But even if you don't like the execution, you'd have to appreciate the irony.
And, each of these games even save your highscore. Incredible, a GTA minigame is given options that many standalone shmups out there (see Gunbird SE or Strikers PS2 PAL) lack!
Excellent job, Rockstar! In the next GTA I want to find a commodore amiga inside a house, to play Menace and Blood Money!

P.S. To have a taste of Rockstar's incredible sense of humour without having to buy the game, have a look at these sites:
www.degenatron.com
www.exsorbeo.com