Mini or Tiny versions of shooters

[Ed Oscuro]

Kengou mentioned that there's a "Tiny Phalanx." So the list grows to six - there's Daioh Gale, Tiny Xevious, Force Gear and Twinbee Returns (from Tokimeki Memorial on PC-Engine), Tiny Tank...wait, scratch that, that's just five.

Small versions of big shooters seem like an interesting (if not good) idea. How many of them do we know of?

[Dragoforce]

Probably doesn't count, but you cand fight the boss from Gradius in Blades of steel. I believe there is a small part of Galaga featured in the loading parts of Ridge Racer as well?

[Herr Schatten]

Legend of the Mystical Ninja (SNES) has a fully playable version of the first level of Gradius.

[Zeether]

The second SNES Goemon has one level of XEXEX too (the second stage to be precise)

[Mortificator]

Mortal Kombat 3 / Ultimate MK3 / MK Trilogy included a Galaxian clone and Trilogy also had a Space Invaders clone.

[PC Engine Fan X!]

Pocket Ray is included in both the JPN and USA versions of PSX Ray Crisis for your perusal. Taito even went all out with a cool and very stylized "Attract" screen + BGM tune for it.

PC Engine Fan X! ^_~

[StoofooEsq]

Ridge Racer lets you play one round of Galaxian when first loading the game. Likewise, placing first on the final track in Ridge Racer 64 has you play the first bonus round of Galaga '88 immediately afterwards; destroying all enemies unlocks the Galaga '88 car (it had hilariously bad grip, IIRC).

[BrianC]

Arnold Palmer Golf for the Genesis has a hidden mini version of Fantasy Zone. Lotus II for the Genesis has a hidden version of an Amiga centipede like game named POD. Goemon 4 SFC has a hidden game based on Time Pilot. Goemon DS has a hidden one level version of Space Manbow (which only shows up with Goemon 1 and 2 GBA in the cart slot) and a version of Quarth (which doesn't need Goemon 1 and 2).