Serious Sam Advance for GBA is the most horrible shooter I've ever played. Its movement system causes more and more resentment after each minute; fortunately, it's possible to run-strafe and turn at the same time, not like in most console FPShooters.
Turnings are also horrible. They are fast, but it's difficult to aim exactly at the enemy (especially who is far from you), and find optimal angel for running without doing an extra turn.
Shooting system is also crappy. To shoot the enemy, you must wait until your crosshair changes its form (and height, if the enemy is lower/higher than you), but sometimes it doesn't change and, if you shoot, you automatically miss. Maybe rockets and missles still can hit the target if the crosshair didn't change in time.
The current WR is 28:52, by tapioca. https://www.youtube.com/watch?v=Dl2ZXo7EChk
I don't know how she (he) manages to do so good speedruns of this horrible game (music is nice BTW). I wish her (him) luck and strong inspiration to make a close-to-perfect speedrun because no-one is going to TAS this game, I guess, and I'm not going to do so.
Everyone can continue my work!