Steam announced today (11) that Metro 2033 is free for a limited time for the PC in the online store. The game can be added to your library until next Monday (15), at 14h (Brasília time). Access the game page through this link.
In addition to the title, the other games in the franchise are on sale. Metro Last Night Redux is 80% off, costing R $ 7.39. Metro Exodus, on the other hand, has a 66% discount and is leaving for R $ 25.49.
Also on Thursday, Steam experienced instability for a few hours. According to the Down Detector website, the problem started around 4pm.