Games Like Unidentified

The government has been attacked by unidentified creatures, and you, as a mercenary, was hired by the government to clear all the threat.
An FPS game which you can fight with those cunning creatures regardless of the weather, day and night change. Earn more and more reward to buy better weapons!

features:
A fake OS system.
Three location.
Randomly generated event.
Randomly generated creatures.
Randomly changing weather.
8 types of weapon and Syringe.

Please note that this game doesn't have a save system.