Beating the Galaga minigame in the initial loading screen as fast as possible
Emulator used: BizHawk 2.4
About the movie
Well, it turned out this minigame seems to be TASable, to I TASed it.
Destroying the last two enemy of a wave in reversed order: this saves some time because it makes the last enemy of the wave disappear early, at the cost of delaying the other one.
Destroying two enemies at the same time: your ship fires two bullets at time, and when one disappears, the other one does as well. However, if both bullets hit two enemies at the same time, both enemies will be hit. I have managed to hit one enemy twice with both bullets, which allowed to destroy instantly despite the fact that had 2 HP.
Not sure if this technically counts as a "full game" within a game.
One could also argue it breaks the "exists separately on the platform" portion of this rule, although I'm not sure if Galaga in single-game form was ever released for PSX. It certainly breaks the spirit of the rule when taking into account the Use the correct version rule.
However, as a counterpoint to this argument, this TAS presents a unique opportunity to see double-ship action, since my understanding is that a full "All Challenging Stages" TAS of standard Galaga would likely skip getting double-ship because the time loss to obtain them is too significant. But by the same token, a double-ship TAS variant could be created for a full game Galaga submission, which would be more "complete" than this movie (though it may still be ineligible for publication, given that it would likely have to mean Moons criteria, since double-ship seems too arbitrary to be Vault eligible).