The following shows the differences from the NES game that considers this game its own.
Faster than the NES
This game was the first ever Contra game released in arcades. This version appears to be much shorter than its successor on the NES, making the game run at a much faster pace, especially for speedrunning. When looking into its stages, you can see that they are all much shorter than the version you see featured in home consoles; This can be seen with all the stages in the game, especially the last few stages, where Snow Field, Energy Zone, and Alien's Lair have all been combined into one (Bunker is instead a part of energy zone in this version).
The Laser
The way weapons work in this game is slightly different then that of the NES version. The weapon labeled R (I couldn't find an official name for it) is in this version as its own individual weapon rather than one that speeds up the shots of others; the Laser is much more powerful in this version compared to the NES version, making its DPS superior to even the Spread Shot when close up to an enemy. This is why you see the Laser being used for the entirety of the run. It is used for a wide variety of tasks, weather its to obliterate enemies from afar, or close up. Speaking of which...
Now that you know two major differences, I want to now explain each stage and why the TAS decides to play the stages as shown...
Jungle
The first stage in the game. It already appears to be much shorter than its NES counterpart, and it shows by how quickly the stage is beaten. This stage has a pretty standard goal. Get to the end and destroy the wall. That's what our old friend Bill does in a matter of seconds. He had to jerk to the left for one frame or else the enemy behind him would have assassinated him.
Base 1
Pretty boring stage to be completely fair. All I did was shoot the exposed parts as soon as I could and moved on
Garmakilma
The boss for Base 1. Garmakilma has a weird pattern to the point where the TAS may not have finished as fast as it could have. If anyone has suggestions as to how I may be able to make it faster, please let me know.
Waterfall
The quickest stage in the game, and the perfect time for Bill to practice his gymnastics skills. Once he reaches to top he pulls of a matrix by nearly avoiding all the projectiles presented to him.
Base 2
Same as base 1, but a slightly different layout, and boxes. Moving on...
Godomuga
He loves being invincible. Bill destroys the Cores and gets ready to kill him in what took me 4 whole cycles. This is actually more than a RTS, but only for the reason that the game difficulty is altered compared to that of a real time run.
Snow Field
This stage is almost three times as short as its NES counterpart, but it makes it up by shoving multiple enemies at your face, ones that were all either shot down or avoided by our protagonist Bill. He even managed to confuse two soldiers below him who couldn't help but keep shooting ahead of them. The boss of this stage in the NES version decides to assaut bill right at the start, but as you can see that didn't work one bit. A few hitboxes abused later, we see two Dorgas, the truck minibosses from the NES version. They apparently love to be shredded to pieces for a living as you can see by Bill giving them what they want and deserve.
Energy Zone
The enemy base; its the final stretch. We are introduced to Gordea, the boss of this stage on the NES version right at the start. Bill decides to confuse him by jumping at the right time to make him jump over, and never return; I guess bill was too much for him to handle. A couple flames later he shows up again, thinking that he had toughened up from last time, but that was not the case for him at all. A few spikes and minecarts later we are finally at the last stage...
Alien's lair
All I can say now is that the Aliens didn't know what hit them
This is the first TAS that I have ever submitted to this site, so in case a preview of the TAS is not visible, you can find it here:
Anyway thanks for reading. If I could make improvements or broke some sort of rule, please let me know.