the leaderboards on retroachievements suggest that the one-cycle boss strat has been known since 2022, but it may have been known for longer since it's easy to discover on accident like i did. this is the first video to my knowledge, and the first submission on speedrun.com that finishes the boss in one cycle. the boss fight is poorly optimized, so if you want to steal a speedrun wr, this one should be pretty easy to snag.

may i perchance step up to the plate? :3

I'm pretty sure it is allowed. Most of the runs I have submitted have the 30 life code.

I don't know where you can get it for PC but it's about $20 online for PS2.

A good game to start speedrunning is Contra III / Contra Spirits. The game is only about 20 minutes long and there is only one major strat which is weapon swapping with the Crush weapon.