Hey this cool article from Gaming Hell does a better job explaining what this game's all about: https://www.gaminghell.co.uk/UnderFire.html

The important thing here is that this game uses infrared technology so the game doesn't flash every time the player shoots. I TASed this game to see if it was possible to 1 credit clear. This TAS proves it's possible in theory but my conclusion is that it's highly unlikely, or at least incredibly difficult, to 1 cre3dit clear in real time.

Firing rates

The default gun shoots 3 bullets in bursts every time the trigger is pulled and has sustained fire when held. This means each pull of the trigger normally spends at least 3 bullets. Each bullet has 4 frames of not allowing another shot, so the firing rate is up to 15 bullets a second. The Full Auto power up gives a high capacity clip that allows for single bullet shots to be fired at a time per pull of the trigger.

The shotgun shells don't share the same cooldown with the main gun and can be fired simultaneously. There's probably also a certain rate for shotgun shots but I didn't check as it would be a waste and bosses have invulnerability frames anyways.

Enemy waves

Each round has stops where the player must take out waves of enemies before moving forward. For the most part this advances when the last enemies spawned are shot down. Thus for speed the last enemy spawned should be killed on the first possible frame as well as being the last enemy killed.

General boss strategy

The main strategy for bosses is to use the limited shotgun blasts to damage the boss every time they're vulnerable. Every time the boss gets hit by any damage source, they have about 44 frames of invulnerability before they can get hit again.

The Round 3 boss, the big semi-truck, is different where it can get shot rapidly as it has no i-frames. This means that the fight isn't really slower without shotgun shells since the rapid fire of the main gun works just as well in terms of damage output speed.

RNG and manipulating it

This game has RNG on item drops when background objects are shot, when the boss decides theirs next attack, and where some enemies and/or innocents spawn in certain areas. This can be affected by when the player shoots so a lot of items can be manipulated by shooting at different times. Badges are pretty common drops, while shotgun shells and extra Full Auto pickups are pretty rare in comparison. This makes getting item drops in real time play pretty much unpredictable.

Enemy spawns that do get randomized are mostly important for the Accident Rounds that appear when the player completes Rounds 2 & 4 below a certain amount of credits used. The enemy and innocent target spawn points are heavily randomized here and essentially can't be memorized. This isn't a problem for TAS play since that doesn't really affect speed but poses a huge problem for real time play as it requires intensive reflexes for a given time span.

There are some fights where it's possible to get extra item drops during the fight by shooting background objects. Those fights rely on avoiding background objects with the shotgun blasts unless there have been enough shotgun shell pickups obtained to take out the boss without having to fall back to the main gun.

I could have manipulated one of the balloons at the start of the Round 1 boss fight to drop a single shotgun shell to save some time. The problem is that I realized that too late far into the TAS and it would require a lot of RNG adjustments to get back there.

I collected a bunch of badges just for fun since I could manipulate those drops. I also mostly kept the accuracy bonuses as high as I could. These do add time to the countdown at the end which does waste a bit of time. A notable way to save precious frames would be to intentionally shoot a whole bunch off target and not gather any badges, but that wouldn't be any fun to watch.

Here's an extended input where I put in my initials. I still just let the end of the game play out, foregoing an extra boss bonus.

nymx: Claiming for judging.

Darkman425: Cancelling due to known improvements. I'll probably just do another submission when I get in the groove of looking at this one again some time in the future, but not right now.