Killzone: Liberation was a PSP game released in 2006. It was a follow up to the original in the series, taking place a few months after the first game so putting it before the follow-up console game of Killzone 2. Liberation is now releasing for PS4 and PS5 as an up-rendered version with a few new features like quick save, rewind, and custom video filters. Normally it would cost $10, but if you owned a copy on PSP you can get the up-rendered PS4/PS5 version for free. And here's the thing: there's a good chance you're like me, and "own" the PSP version and maybe don't even know it.
I never even owned a PSP, so how do I have a copy of Killzone: Liberation? Well, do you remember the Sony Hack that ended in a class-action settlement? Part of that settlement was a bunch of free games on PS Plus. So if you had PS Plus back around 2011 when the settlement went down, you might have a free copy of Killzone: Liberation sitting in your vault; and if you do, just head over to the Playstation store and claim your free copy for PS4/PS5. It worked for me!
https://store.playstation.com/en-us/product/UP9000-CUSA37874_00-UCUS986460000000
Unfortunately, Sony Interactive Entertainment aren't putting a whole lot of press behind this one so there is no updated release video or media surrounding the up-rendered version, so here's the original trailer from more than a decade ago for nostalgia...
