This sounds a bit like comes from Resident Evil... Try to survive in a military complex infested with the undead and riddled with the ashes of corporate corruption and scientific hubris.
Walking over a weapon or item allows you to pick it up and put it in your
inventory, which is displayed as a 4x4 grid in the Inventory panel (shown by
default).
Right-clicking on that weapon or item will allow you to equip it for
use (weapons), or to use it on the spot (health packs, derms).
When zombies or enemies see you, they will approach your position and begin
firing. They are very accurate and have weapons exactly as powerful as yours -- be quick to gun them down! If you are killed, you will re-spawn at the last
checkpoint area you crossed.
Some areas of the game will trigger conversations between you and your commanding officers and support staff, and others will trigger a tip, which you can disable at your will. Walking onto an "EXIT" tile will allow you to go to the next floor.
Try to survive, and make sure to keep an eye on your ammo and health!