Actually the game was named S.T.A.L.K.E.R:Oblivion Lost intially but later got changed, many locations were removed and others added. You can check in their website, some old fan art and screenshots. I first read about it in SKOAR...lolz
Free roam is vast when you actually explore every corner, and its quite surprising that how unpredictable it is when you visit the same area after some time or a major event. Last time I had almost all the armors except one important exo suit, but then i reformatted XP (some troubles). Lost my saves too...lulz. Tried some glitches and tricks to enter restricted areas...freedom armory
and blowing Freedom guards without becoming their enemy
It was fun. Getting artifacts at locations you could never thought of reaching. The path to them is not straight. Looting dead bodies...got many modified weapons by this way. It was indeed great fun...except for when you are in underground labs, its damn scary and you will never try to enter them again.
Let me tell you about some monster and their abilities:
Bloodsucker: It can accelerate fast enough to reach you in seconds and it remains invisible except for glowing eyes when it sees his enemy. Only when he claw attack is the time it will become visible. Its damn hard to kill it, the trick is to aim the head.
Poltergeist: These are in lab and you cannot see them but just a faint spark. They can levitate objects and throw at you, it was real spooky when I first thought wtf was lifting crates and throwing at me. It took some time to show some courage and find out that there was something bad with the air floating light sparks. Used shotgun and zapped them all.
Pyrogeist: This is fire monster. It is invisible too except for a when it starts making fire streaks in air out of nowhere and then you know that you are a burned chicken.
Human: Bandits, duty, freedom, military, stalker and monoliths are damn intelligent. If you stop at one place you have absolutely no chance of survival. Key is to move and take them strategically. Infact at later levels the difficulty increases with great weapons and armors.
Snorks: you will know what they are. Pretty annoying freaks.
Zombified stalkers: whats the reason for zombies in this game ? You will know and the reason is quite scientific. You can spend thousand of bullets to kill them but they wont down until you shoot their head. Or better a single swipe of knife can take down in one try...ironically. But dont take them as dumb slow zombies as they know how to play with gun.
Pseudogiant: Am afraid I never had one on one close quarter combat with it. It can crush you and make seismic waves in grounds.
Controller: Probably the most intriguing villain. It can control your mind. I wont spoil what it does. Better see for yourself the uneasiness and high pitched brain melting sound.
Othe mutants: yeah more are there but alone they are pussy. If they are in pack they will attack you to make a meal. If they are alone they will fled away.
I guess its enough to make it interesting.
and so lost all my save games.