Bottom line: Steam is celebrating Alien Day with discounts of up to 95 percent on select Sega games from the Alien franchise. Considering Alien Day technically happened yesterday, it's unclear how much longer Valve will continue to run the sale so if you see something you want, I would go ahead and nab it sooner rather than later.
Alien Day, similar to Star Wars Day, is observed by fans of the franchise each year on April 26. It is a reference to LV-426, the moon on which Aliens is set.
For a limited time, you can nab Alien: Isolation for just $2 on Steam - a whopping 95 percent off its normal $39.99 asking price. Optionally, the Alien: Isolation Collection includes a full complement of downloadable content plus the core game for only $12.49, a 75 percent savings.
The Alien Bundle, meanwhile, includes the entire Alien: Isolation Collection as well as the Aliens vs Predator Collection and the Aliens: Colonial Marines Collection at 80 percent off, yours for just $20.94.
A fun fact about Aliens: Colonial Marines - originally launched in 2013, the game shipped with a coding error that severely impacted how the AI behaved. A simple patch greatly impacts how the enemies respond and thus, improves gameplay tremendously.