These are the notes I made while working on this run:

Stage 1

-the car and the first grenade launcher score 4060 -ground turrets 500 -snipers 790 -ground soldiers (red and blue) 180

I kill everything and count 46 aliens (including snipers and grenade) got to the base mid boss, kill the 2 bomb launchers (perhaps this is not necessary, but eases the positioning) then do the glitch using a bullet from the sniper standing on the platform facing left. Is possible to do it being hit by a ground troop, but that was the more consistent way I could manage to do. Grinding the score here to get over the 20k will help to depend less in enemies in stage 2. I usually end this stage around 34k (end level 10k bonus included)

Stage 2

• soldiers 180
• green worms 400
• pods 2000
• landmines and each boss "leg" 500

I kill everything that is fixed (all but soldiers and worms) that sums 44k so I know I'm around ~78k , then I have to get at least 600 killing enemies (+/- depending on stage1 score). Many times the scoring was off, I guess is because the score when enemies die of exploding landmines is different (many times they die off screen), or some weird scoring mechanic, some times soldiers overlap with each other so that is another thing to keep an eye.

Stage 3

-rolling balls 710 -sniper 790 -bomb power up 5

Here I couldn't replicate normal/hard strat, neither by throwing myself into the pit, nor killing both enemies at the same time. The way I found seemed to be the more consistent in my attempts, but I might be missing something about normal strat. Sometimes power up values can help reach the required score, I think the "F" power up is around 200, but can't remember exactly) If you are under 79300, kill the ball, if you are over, avoid it and let it go. Scroll a bit so the sniper is only about half visible, step out of slope so 1 leg is in the air. This appears to give enough time to despawn the character and distance for the explosion to get the sniper at the right moment.

Stage 4

-bikers 7000

Because I can't grab the bomb in stage 3, I have to game over to have a bomb. Then first I grab the weapon power up, I'm not sure why when I didn't do it I failed the trick, most likely coincidence haha, because the power up score shouldn't matter. Get to life 0. The glitch can be done by killing 3 bikers with 1 bomb (21k for the extra life from 0 points) but the way that appears to be more consistent is killing 1 before and then 2 with the bomb, I wait and position myself to the left side, and try to die with the trail of a grenade explosion, some times it doesn't work because there are not enough bikers or the bomb active range can't kill 2 on time. Killing 2 before bomb can work too, but was hard to be despawned at the 1up. This should finish the stage with ~31k

Stage 5

-pods 2000 -ants 200 -red worms 300-900 perhaps 1200, this one is weird, I tried counting killing it all, some parts, before and after it splits, and got different results, anyway I avoid killing this

• boss claws 35

Here I just try to not die and not kill any enemies, regular ants should be fine, and max 1 red worm. Since you have to kill at least 1 red ant to destroy the pods that give us 11k, boss damage score seems to be around 11k, and end level 10k bonus should leave us around ~63k plus enemies killed, don't use other weapon than machine gun or laser, got way more points using other weapons.

Stage 6

-aliens 1200

Here I just have to do the math (80000 - ~64000)/1200 That means we need to kill around 13 to 16 aliens for the extra life, I get that number and subtract 2, to try to get those with the bomb, just like bikers it can be done with -1 or -3, but this seemed to be more consistent, also I still don't know a consistent place to do it, many times I did the glitch (stayed alive) but couldn't despawn the character in time, this was the more random part of my attempts.