Alien Syndrome on the NES is more of a port of the Arcade game than the SMS version.
User Rating: 6.5 | Alien Syndrome NES
Alien Syndrome has a simple premise, rescue all of the hostages in six zones with enough time to spare to fight the boss. Alien Syndrome on either the NES or SMS play essentially like Ikari Warriors, but in enclosed areas. The NES game actually mirrors the arcade's level design and enemy closer than this SMS version does. For one reason or another the SMS version of Alien Syndrome (1987) has the levels split up into different screens that switch in the same way Zelda did on the NES, but the colors, sprite sizes and music are superior in this version. The NES version (1989) has all of the level at once, with smooth scrolling between areas, the same enemies that the arcade game has, but the graphics consist of the extremely limited color counts that make the entire screen look more or less like a Gameboy title with colored sprites. Perhaps the most significant difference between the SMS and NES versions is the way in which the enemies appear. On the NES aliens might appear as the screen scrolls or when there is a visible spawn point on screen that usually looks like some kind of egg sac or mouth. On the SMS aliens spawn at random places around the static screen you find yourself on, often times right next to you and after you kill them they can spawn again but usually not in as many numbers as they did originally. This causes the SMS game to be much more difficult than the NES game. Alien Syndrome on NES not nearly as intense, but it carries much more similarities with the arcade version. The arcade and NES versions' 2-player simultaneous gameplay is replaced on the SMS version 2-players taking alternating turns. Owning both the NES and SMS versions is a great idea, as the former will provide an easier and more 2-player friendly experience and the later provides much better graphics and a greater old school challenge.
- Whatever you do, do not judge a game by how it plays in emulation. 
