Speaking of true pain, Rolling Thunder is excellent but basically impossible. After being stuck for approximately the length of my life to date on level 8 I cleared 9 pretty quickly and felt like I might see the ending pretty soon. I’ve reached the last boss, but I can’t beat it yet.
This map’s from vgmaps, by the way, with the letters added by me. So here’s how this goes:
You start at A. Immediately duck and shoot then walk forwards to hit the yellow crawly guy before he jumps at you. Then switch to the top level, walk forwards to just before the opening on the lower level, duck, and start shooting all the enemies that jump up. Move above the opening below, jump down and move to the back. Shoot the guy there if he didn’t jump to the top earlier. Go in the door (B) for extra bullets, but be sure to enter the first half of the door so that the crawly guy who’ll appear while you’re in there will walk off the left of the screen instead of turning back and messing it up. Walk forwards to just past the second opening. Another crawly guy will go past. Move forwards, switch to the upper level, and jump forwards over the edge. On landing, duck and fire four or six times depending on whether the yellow dude has moved to the background. If he has, wait for him to walk past the opening (D), then go through it. Move forwards to the door at E, shooting any guys that come through the two doors on the way. Go in E for 80 machine gun bullets.
At this point you’ve got two choices: carry on and face the boss with the pistol, or re-enter the door a couple times to get machine gun ammo. I’ve died against the boss several times with the pistol, so I’m currently trying the latter option, but for some reason I haven’t been able to clear the second-last room (S) with the machine gun so I haven’t been able to take the boss on with it. Anyway, if you’re gonna try with the pistol, then skip the next paragraph, and make sure to stop in at all the bullet doors for the rest of the level. If you get the machine gun ammo, skip the bullet doors because you won’t need them and you’re at risk of running out of time.
If you want more ammo, you need to move far enough from the door that it refills. I’ve found that point C is far enough. Go left, killing any enemies that might have appeared, and switch to the upper level at about point D, then move left and jump down. You’re aiming to land on the crate at point C, then immediately walk off it to the left, duck, and fire twice to kill the purple guy. If you overshoot the crate, you’ll land on the purple guy and die. I find jumping at the second last yellow bar works. Then turn around and shoot the orange guy that’s probably appeared. Duck his bullet if necessary. Shoot a few times to stop any foreground enemies shooting you and jump over the crate, then shoot a couple more times and move to D again, go through, and proceed back to E for more ammo. Go back to C again to get one more fill so that you have enough to reach the end of the level.
Once you’ve got some machine gun ammo from E, move forwards to F, go to the foreground, and move forwards to G to scroll all the enemies behind you offscreen. I’ve found that if you don’t enter the door at E as soon as it’s possible and do the same at F, the enemies will catch up to you. At G, watch for two enemies who will move over the crates to you. Once they’re gone, jump up between the purple guy’s shots, and shoot him and the other guy that’ll come on screen as you do. If you’re lucky the front one will only go back a short distance and you can shoot him again. If you’re unlucky he’ll fall into the gap between the four crates and the single crate and stay there. He shoots out of sync with the other enemies here, so the next part will be harder if he’s down there. Jump to the upper crate (H), then jump straight up. This will cause the enemies to lose sight of you and stop shooting. Move forwards one crate, duck, and shoot a lot to take these guys out, then move down, shoot some more, and move forwards. Watch out for the guy who jumps down to I.
At point J a guy will come through the door. Shoot him, then duck and shoot a few shots and move forwards then duck and shoot again. There are three crawly guys and two walky guys to take out. Then move forwards to K and jump to the upper level. If you don’t do this immediately a guy will start throwing grenades making it harder. From the upper level, wait for the grenade guy to turn and walk away then drop down next to the crates and shoot him and the guy that comes through the door. If you wait in this area briefly the guys at M will move forwards and hopefully jump to the upper level. Jump up at L, shoot everyone up there, watch for guys coming through the doors, jump down at M and shoot the guy to the left if he’s still there then turn to the right, shoot a couple times and move forwards. After jumping over the crate at N, try to get to the next one before firing or ducking. This will stop a purple guy appearing to the left. If he does appear, stay ducked. If you try to turn while ducking, you’ll stand up and get shot, but if you fire and then quickly turn you’ll stay low. Move forwards, shooting before jumping over the crates to take out the guys about to appear, and move to the upper level.
At point O, wait on the edge for the crawly guys to turn and walk off the right side, then drop down, duck, and shoot the crawly guy that appears and the walky guy that does the same. If you’ve got the machine gun you can try dropping earlier and shooting the crawlers, but I don’t recommend it unless you’re low on time. From there, shoot a bunch to take out the guys that’ll appear and move forwards. At about point P three panthers will jump from above. Duck before where they’ll land and shoot them as they do. At Q two purple guys will come at you, just jump to the upper platforms and avoid them. At R wait before dropping down for the crawlers to clear out, then drop and shoot the guys that appear.
Now the tricky part: At point S a hidden guy will appear when you get near. Shoot him. He takes four bullets to kill, or he might turn around and walk off. Another four of these guys will appear, one on each of the steps and two on the last step. You gotta get close enough for them to come at you, but avoid getting hit when they do, then shoot 'em. The last two are the worst. High jumps from the steps seem to be the only way to get them to move, but you’re stuck in the animation for so long that they often hit you when you do.
Now the boss: Drop down at T. If you have the machine gun, just shoot until he dies (I think, I haven’t managed to get here with it yet). With the pistol, shoot a bunch, but stop in time to jump over him as he runs towards you, then turn and shoot and jump over again, repeat until dead (again, I haven’t managed this yet).
Slip up basically anywhere and you die. I wrote this from memory, so maybe that tells you how many attempts I’ve made.
I’m playing this on PSP, which lets you save after each level. How anyone would ever beat this on an arcade cabinet that limits how many times you can continue I don’t know.