Hope to start a guide to this when I get the time- here are some of my observations & strategies, some of which may be incorrect :)

Boss fights:

Grenade drops are the limiting factor here- easy to run out, and the gun is very slow. If you have to take out more than 2 bars of health with the gun, you lose a lot of time.

Boss hitboxes on levels 1, 2 and 3 are weird. For instance the 1-4 boss takes a lot of damage just below the highest propeller- the top half of the ship. Boss 4 & 5 seem not to suffer from this. The hitbox on boss 3 (the truck laying out the guns) is the most confounding to me. I have 20 second differences between fights that, to me, seem identical.

General strategy:

1. Kill every green colored enemy. Each kill moves the level's progress bar up one point. Prioritize soldiers over vehicles when you have to choose. Gray enemies do not progress the level.

2. Take out all slow-crumbling scenery, but not necessarily every piece of scenery. Some levels require a full clear, while others may be faster to execute by just taking out certain features. There are some painfully slow scenery crumbles such as the foreground concrete wall in 1-2.

3. Get as many grenade drops as possible. Grenades love to drop out of bushes periodically, especially at the beginning of the level. Grenades will not drop while a bonus star is on the screen, so collect the stars whenever possible. Collecting grenades is often slow and deadly, so getting lots of drops early and carrying over your grenades saves lots of time later.

4. Don't die, but if you die, sometimes it loses no time, or minimal time. My best runs have several deaths.

5. Red and Blue power up guns are convenient, but don't deviate too much to grab them. They aren't that much better except in certain situations that become obvious the more you play.

6. Don't destroy scenery with an enemy behind it. It will de-spawn the enemy and you won't progress the level.

7. Finish levels in the middle of the screen. If there is a scenery crumble you have time to run there. If not, try to fire your last shot from the middle. Loses tons of time if not done.

Other thoughts:

This game is excellent for speedrunning. Lots of predictable patterns but still plenty of random variables like drops and enemy aim keep it spicy. Plus the occasional invisible bullet or inexplicable de-spawn. No lag though. The game sometimes spawns enemies a few tenths of a second faster or slower, but it's pretty consistent.

Dive-rolling vs Running. Both are useful at times. Dive-rolling is slow but if your timing is good you can avoid explosions and bullets, especially when you're in a corner (very useful on 1-3 and final boss). Running is fast but so often gets you sniped.

Comments on a few levels:

1-1: House on the left is a slow crumbler. Prioritize it but don't de-spawn an enemy behind it. The rest of the scenery can stay up. It's probably just humanly possible to take out all the scenery with a gun drop or two. You can force 2 grenades (or guns) at the start by the bush. High drop rate for grenades if you mind the stars.

1-2: Really difficult to take out the slow crumbling right walls (3 sections) without de-spawning enemies. Good times can vary by 6 seconds because of this. Concrete wall in front is slow too, so take that out.

1-3: Don't destroy the gate in the middle. Saves at least 15 seconds. Hard level because the middle gate enemies spawn quickly, usually right when the side enemies or grays are trying to snipe you. Take out the warehouse on the left if you have time- it's a slightly slow crumble.

1-4: Take out all scenery/cover. Target top half of the airship. Can be done shockingly quickly, but the timing is intense.

That's it for now, cheers.

Current time for me is 20:05. Sum of best is 18:51.

19:52 now. Looks like ~19:30 would be a great goal and a hard time to beat.

19:45 now, getting more consistent. On 1-1, it is in fact just barely possible to take out all the scenery and finish in the center of the screen w/out missing an enemy spawn. Saves just over 1 second, so it's not worth it unless the game becomes competitive. The slower strat is very easy by comparison.

In 2-1, a tank spawns every time a tank is killed, so this level can get super fast by carrying over a high grenade count from 1-4, and throwing grenades from the left side of the screen. The pattern for the lake enemies is pretty simple but hard to keep on top of. Taking out helicopters immediately should help there, but that requires an even higher grenade count. 20 or so should be good.

2-4 boss can go down extremely quickly by standing just right of center and spamming grenades, while inching to the right. But you get shot frequently and it's hard to avoid while keeping the good grenade rhythm.

Major time difference between a grenade lobbed on the player's y-axis, vs a grenade lobbed far across the x-axis.

Congrats to NESCardinality on the 19:38! It was a really nice, clean run with good grenade use.

I'll see if I can make you work a little harder for it ;)

19:26. Back to you, sir.

I'll upload soon w/some commentary. 19:00 is probably a real thing. 19:15 feels attainable.

ed: lol, sniped by 2 seconds almost immediately after taking it back. c'est la vie, touché, and baguettes.

18:39 PB now, and runs that get past 1-3 and the ever-confounding 3-4 boss are clocking 18:58-19:15. Sum of best individual stages is 17:53.

Maximizing grenades:

It takes a while to get the feel for it, but timing your building destruction is really crucial, because every enemy you kill while the bonus star (points only) from a destroyed building is on the screen- or a powerup gun- cannot drop a grenade. I use 30+ grenades on each boss so this is the key now, besides just executing well and not dying. Also, hitting as many enemy projectiles as possible is important, because those drop grenades too. Finally, I think I can confirm that killing grey enemies is what spawns the "grenade medics" that you can shoot for drops, though it will only spawn them occasionally. They seem to spend a random amount of time on screen once they come out. I'm carrying way more grenades now that I'm paying close attention to this, which I think accounts for a lot of the improvement.

Looking at my splits, I think my max on this game is realistically 18:2x, though it wouldn't surprise me if somebody with a lot of skill eventually pulls off an 18:15.

Another 18:39 and lots of 18:4/5x the last couple days. Mostly due to improvements in early consistency and sussing out good strats for levels 4-5. Found that I was despawning too many enemies behind destructible scenery which was eating ~5 seconds per run.

3-3 loses 4+ seconds if you miss any spawns- that's the most punitive level, but thankfully it's an easy one. The building on the left is the cause. Put some damage on it at the start, and then finish it off immediately after any enemy runs out from behind it. (3-2 has a similar issue but only costs >2 seconds).

4-2 is an absolute madhouse. Take out the church, the arch, and the two big pieces of scenery below the arch. Can be done without missing a spawn, but it's not easy. This is a make-or-break level for low times. Easy to lose 10 seconds here if your cover is blown up and you have to dodge a lot.

Alternate kill for 2-4 (submarine): Stand dead in the middle and spam grenades. 36 should do it, but 30 usually works if you finish off with the gun quickly. If you get sniped by a bullet here, it doesn't lose as much time as hiding in the corner of the screen. The post-death invincibility lets you finish it off quickly. Often you can get lucky and not get shot at all.

Here's a stage-by-stage write-up of my shiny new 18:23.

1-1) 38.58 (gold: 37.04)

Standard 1-1. Acquire grenades, take out the house on the left. The gold involves destroying all the scenery and finishing in the center, which is very difficult, and normally forfeits too many grenade drops.

1-2) 44.73 (gold: 39.99)

Standard 1-2, but I lose one second to sloppy play, letting an early enemy through. The gold is the same story as 1-1, very hard but maybe worth doing as it save 3+ seconds, and it's an early reset.

1-3) 44.57 (gold: 43.01)

Standard 1-3. I lose some time grabbing a grenade at the end, and I missed one center spawn, but I'm happy with it. Grenade count looking very good.

1-4) 1:07.33 (gold: 1:06.10)

Nearly perfect 1-4. Got lots of drops, and got the quick kill on the boss. The only way to save time here is to dive-roll toward the center just as you throw the last grenade, but I gave up a second to make sure I landed the last one.

Level 1 Split: 3:15.22

This is a very acceptable split time for Level 1. More importantly, my grenade count is huge.

2-1) 34.92 (gold: 32.36)

Standard 2-1. Slightly imprecise and slow. I could have spawned the tanks sooner by killing them quicker. Totally acceptable time though.

2-2) 45.64 (gold: 43.04)

Pretty bad 2-2. I miss some of the weird hitboxes and get totally out of position, losing 2 seconds. Overall the run is still in decent shape.

2-3) 1:11.02 (gold: 1:09.11)

Bad 2-3. The time here should never be less than gold. I take a sloppy death and lose one spawn, then forget I lost the spawn, and it takes me forever to shoot the last enemy as I expected the level to be over. Unacceptable 2 second loss here.

2-4) 55.17 (gold: 48.80)

Good 2-4. I only miss a few spawns (which is normal- this is a tough stage), pick up some grenades, and clear the scenery efficiently. I lose a few tenths because I fat-finger pause the game while dive-rolling, but no big deal. The boss fight is totally standard. If you're agile and lucky, you can dodge all the submarine shots, but I expect a death here. It's faster than fighting from the corner.

Level 2 Split: 6:41.99

This is about the slowest split I'll continue playing. You really want to be under 6:40 here. The grenade count (24) is excellent though, and worth a couple seconds in its own right.

3-1) 42.75 (gold: 42.69)

Perfect 3-1. Worth noting at the end is the grenade toss, which has to be perfect, along with sniping the final enemy.

3-2) 1:05.07 (gold: 1:03.81)

Bad 3-2. No reason not to equal the gold here. I accidentally despawn an enemy when I take out the building on the left a couple frames too soon. There is no rush there, just careless play. It costs just over a second.

3-3) 1:09.14 (gold: 1:05.09)

Bad 3-3¤. I screw up here by missing a tank (lol). This level punishes you harshly for 4 seconds if you miss anything. However, I pick up 36 (!) grenades, so there's zero chance of my resetting at this point.

3-4) 1:25.31 GOLD

Unbelievable stage, scorching my previous gold by 4 seconds. The trick is in the boss fight. Previously I've mentioned that fights that seem identical can be 20 seconds slower. I get the 20 seconds here. I think I've figured out how to damage the boss turrets most efficiently, but typically I don't get the kill until the next cycle. I figured sub 18:30 was coming at this point.

Level 3 Split: 11:04.27

Best pace I've ever been on, so I guess no complaints.

4-1) 34.73 (gold: 34.55)

Very good 4-1. This level is sneaky hard. The spawn pattern is the simplest in the game, but they're spread out and some of the far hitboxes are tough. This can get faster by taking out the scenery, but I'm rarely in the mood to try that.

4-2) 40.70 (gold: 32.93)

Disastrous 4-2. I take a "ripple effect" death here, where I lose my cover, lose spawns, then lose time to slooooow crumbling scenery. I actually recovered well not to lose 10 seconds here. I was slightly perturbed at this point but still on good pace.

4-3) 53.12 (gold: 49.06)

Sub-par 4-3. Played it safe here and just gritted through it. Bad level but not a disaster. Took a "meh" death from a ridiculously low-angled grenade.

4-4) 1:02.51 GOLD

Dream boss fight. Took a full second off what was already a tight gold. Grenade count amazing.

Level 4 Split: 14:15.35

Overall a nice pace, but those mistakes were rough. Grenade count (59!) makes up for it.

5-1) 46.18 (gold: 45.04)

Speaks for itself, very solid 5-1. No, that forever-crumble on the left is not destructible.

5-2) 1:01.15 (gold: 58.54)

One minor death that doesn't cost any time. A bad targeting decision does though. Mediocre level but no disasters.

5-3) 55.07 (gold: 54.94)

Great 5-3, executed as planned. The end of this stage is always an oh-$h!t moment, as the second-to-last spawn will kill you if you're off by more than a pixel. It's why I stand just off-center to the left, to give me a chance at dodging if he gets the shot off. It loses a few tenths, no worries.

5-4) 1:25.40 (gold: 1:21.87)

Knew that I would crush my pb if I just didn't choke, had all the grenades in the world. This level is kind of slow and boring if you play it well, and a nightmare if you get behind. Don't get behind. Taking potshots at the greys is good, because it interrupts their attack patterns.

Final Boss: Solid execution. He did make me roll in the corner a bit, but overall it went swimmingly. I was very fortunate and executed well to have 5 good-to-amazing boss fights. For now, 18:23 will keep me happy, though I now know I can pull an 18:15.

Welcome to the leaderboard, @guggensulli. Hope you find the thread helpful, and please share any insights you have, if you're inclined. I think the time will go below 18:00 with the next dedicated push, but it needs runners :)

Yea i watched your WR (18:23) video to help me shave almost 2 minutes off strats i was using a few months earlier. Manipulating that 3rd boss seems like one of the bigger time saves. I thought the boss was random until i read your post above. I guess I'll play around to see if I could find ways to more consistently manipulate the fight. Good luck Disco on your way to sub 18:00!

Been back at it (streaming my attempts now) for a week. Closest I've come is 18:25, 2 seconds off. Have had a large number of runs that were well ahead, but suffered bad luck on the 3-4 boss. Still haven't cracked the code on how to get the hits to register there. I thought I was onto a solution with subtle timings and whatnot, but I think I was just getting a good run of variance.