System Shock 1 is one of the best games i decided to play at some point, to say the least.
Brief history: after different immersive sim. projects (i played and loved Deus Ex 1, System Shock 2, Thief: The Dark Project, Ultima Underworld 1 and *some* more games) i wanted more of same experience - slightly slow gameplay compared to FPS genre games, clunky at times, but providing great ways to explore and interact with world and environment (also, the less scripts in general will guide me throught whole game - the better for experience with game) - and eventually stumbled upon SS 1 with some advises from RoSoDude and other people to how approach gameplay and UI at first.
Gameplay of SS 1 centered around item management (consumables, grenades / explosives, patches, more rarely ammo~), provides options for trivialization (respawn points at most levels replenishing most health and costing only in-game time to do so - as well as using logic probes for solving every puzzle that potentially can hinder progression), have limitations on amount of weapons that player can carry (but this is easy part - some weapons are just BAD [Riot Gun], some weapons just GOOD [Magnum], some weapons going to be found later in game [Skorpion] with small amount of weapons are entirely up to player to use or dispose [Plasma Rifle that i did not liked - or Rail Gun that i liked a lot after couple of uses]) and have enemies that going to respawn after time (if game have no time limit... Medical level can be harvested for medical patches).
Most levels are suprisingly memorable (especially Medical level, Executive level, Flight deck) and have good deal of secrets and enemies to slaughter - some secrets depending on "security level" [0 % and some secret door will unlock]. Reactor level and two smaller Groves are only locations in game that i dislike.
Enemies variety is pretty good in SS1. Every thing you encounter is either organic enemies type (some weapons or ammo types are better against them) or mechanical enemies type (same thing). The closer player to ending the more SHODAN influence become apparent: more cyborgs and robots - and much less mutants.
Attachments are aquired in same way as items - some of them are in secret areas. Something as lantern is life-saver in most areas, just as shield for harder fights. Jump Jet is most energy consuming "ability" in game, but dem - some of the best memories come from using it (especially for first time on same level where i found it).
Story (read: audio logs) and how plot combines itself into game is more forgettable part of game - but it serves required function pretty well and at the same time it gives more reasons to explore and visit different areas. Some logs vital to completing game, so it is useful to listen to them anyway.
This all comes to important part: game replayability lies in bypassing suprising amount of trivialization that player will see with more experience in SS 1. Best way to make game harder and more enjoyable at the same time is in Game Difficulty settings; with time limitations most options to make game much easier are non-existent (medical tables take time, reconstruction stations take time, most tactical cheeze with melee weapons takes a ton of time).
At the same time, completing game with time limitations is extremly hard for first time, without required game knowledge + it robes player out of exploring some locations that are optional.
Other important part: cyberspace levels. I been hearing a lot of hate towards cyber locations and been also hating them at first, but changed my mind later on. Best part of cyberspace: levels are short and usually contain something useful without being vital to game progression. Clunky controls can be changed in DOSBox or in Enhanced Edition directly. Worst part: final battle can be pretty hard for players who been slacking on cyberspace exploration whole game, so i recommend learn this type of levles to a point where completing them is easy.
Conclusion: as i said, great game in it's own right - definetly worth a try. I been not saying anything about controls, because i changed them for my own comfort and best performance during first level - so cannot properly comment here*
