Well, they're both really good games, but different.

The first is more or less a series of horror vignettes strung together with a fragmentary and confusing storyline. I forget the specifics. The detective narrative is clearly inspired by movies like se7en and Saw, but it also branches out in a supernatural direction. The basic gameplay is flexible-stealth type stuff. You can throw things such as bottles to divert enemies, but also use them as single-use melee weapons, and there's the typical array of weapons with limited ammo scattered about. There are big, well thought out boss fights that usually require you to solve a puzzle to defeat them. Par for the genre, there are also some bits where you have to escort a character, which can require a few tries to get right. It was slightly controversial on release, because it was presented in some kind of ultra-widescreen format, and they only provided other options later in a patch.

The first game has a season pass, which is a mixed bag. It has a few extra chapters where you play as one of the side characters, which are enjoyable and in keeping with the kind of gameplay in the main game. There is also a weird FPS chapter where you play as one of the bosses (a kind of pyramid head type character), which, to me, feels kinda forced, like they made it as a contractual obligation or something.

The second one is slightly different in that it has a large hub area with more of a focus on exploration, yet it's got a much tighter, more linear narrative. It gives you a bit more firepower in the form of a crossbow with different types of bolts that you can craft. Most people seem to prefer the second one (it is more consistently fun), but I'd recommend both if you like action-oriented horror games, with the season pass for the first game as a desirable but not essential extra.

It's been a few years since I played them last, so I had to dig back into the memory banks a bit there!

Where is Fallout 4?

wow superb. thanks for the big snip mate

Apparently there's some big "next-gen update" coming later this year or possibly next. I'm not sure there's anything GOG could do to convince Bethesda to release FO4 here at this point in time, though a major release like this would be appropriate for GOG's 15th anniversary. I do think it'll show up eventually, similar to Skyrim.

Still would be nice to see it on GOG, since it is getting an Offline Mode:
-> https://www.videogameschronicle.com/news/redfall-will-recieve-a-final-update-adding-offline-play/