Instead of risking your PC, you can get the real game safely and cheaply:
Here is why that story usually ends in a "Game Over" and how you can find a better path: The Risks of "Highly Compressed" Downloads left-4-dead-2-download-pc-highly-compressed
Many sites offering "highly compressed" versions of popular games are fronts for malware, spyware, or ransomware. Your PC's security is worth more than a few saved gigabytes. Instead of risking your PC, you can get
To get a game that small, "repackers" often strip out essential files like high-quality textures, music, or even the cinematic cutscenes. Extreme compression requires your CPU to work overtime
Extreme compression requires your CPU to work overtime during installation. What should take minutes can take hours, often ending in "CRC errors" because a single bit was lost during the squeeze. A More "Helpful" Way to Play
Once upon a time, a gamer was searching for " Left 4 Dead 2 PC highly compressed" to save some space on their hard drive. They found a site promising a tiny 500MB version of the full game and were thrilled—until they hit the "Download" button.