I'm about half way through the original Half Life for the 3rd or 4th time, and if you have not played it, you should give it a peak. Especially if you like shooters, a most outstanding solo survival setting, a viable gaming experience even 10 years after the original release, and one of the most influential games in video gaming history (my opinion). At the Black Mesa Research Institute, a little experiment goes awry opening a dimensional riff, allowing bunches of aliens to fall through. Priority one becomes escaping the facility alive as you crawl though tunnels, access ducts, the underbelly of this immense facility. Then you discover the military has been called in to "take care" of anyone exposed. And there seems to be some kind of sinister government involvement. It's still fun! If you have access Windows, say via Bootcamp and install Steam, you can buy it for $10 or the entire original anthology for $15. Wiki link. Steam Link.