YMMV / Alien Syndrome

• Demonic Spiders: In the NES version, the multi-sectioned worms in level 4 were replaced by purple mushroom cloud like things. They moved at least as fast as the player, with their shots traveling even quicker. There are ways to evade and kill them without dying, but it is extremely difficult.
• Inferred Holocaust: The Alien Ship crashes into the earth in the NES version's ending. In many versions, you could leave quite a few hostages behind on each ship.
• Nightmare Fuel: The PS2 remake: with Darker and Edgier graphics, a horror-like soundtrack, and grotesque boss designs, all of which are accompanied by a Scare Chord upon encountering them.
  • The remake's soundtrack is particularly skin-crawling, combining themes from the original with demented musique concrete. The two boss themes take the already menacing "Killer Instinct" and twist it into something tense and gnarly. The final boss theme mashes those themes into a mess of noise, orchestral hits, Ominous Latin Chanting, and pure terror.
• Polished Port: the Game Gear version, among 8-bit ports. Instead of translating the anemic Master System port, SIMS Co. made a pseudo-sequel that has Ricky and Mary liberating a single ship. New levels (albeit only 4 of them), re-arranged bosses, more powerful weapons, and a solid soundtrack make this version stand well apart from the NES/MS versions.
• Scrappy Mechanic: The arcade original's short timer. The maximum that the dip switch would even allow was 150 seconds, which isn't much when you need to search a big level for hostages, then go fight a boss.
• Serial Numbers Filed Off: The game is not exactly subtle in its cribbing from Aliens.
• That One Boss:
  • Teetsie, the NES's level 5 boss: a big cestburster-thing whose tongue retracts as nematodes emerge from the top and the boss's mouth.
  • Minenor, NES level 6: the arcade's mutant baby/turtle thing. It now has so much health that even with a much longer timer and having taken an efficient path through the level, beating it is still a race against the clock.
  • King Core in most versions. This ghastly head breathes in tornadoes so rapidly you can barely dodge them. Even worse on the PS2 as they can one-shot you.
• That One Level:
  • Level 3, in most versions, has you dodging spider-like creatures that hop and fling their eyes at you. All this while crossing even more bottomless pits than level 2. The PS2 remake, especially on Retro Mode, compounds this as your health bar is rendered moot.
  • Level 4 in the NES version has the above mentioned purple mushroom creatures, now with spawners that can't be destroyed.
  • Level 5 in most versions. You encounter brains that burrow out of the floor in droves, which'll cost you big if they jump you.

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