Thanks everyone for your suggestions! I have a lot of catching up to do!

The Suffering Prison is Hell

and Ties that Bind

Can't pick one they are both awesome! And neither is on Steam.

No one mentioned the Might and Magic 6-pack so far??? It's one of the best deals you can get on GOG.

I second Alpha Centauri. It's hard to believe such a jewel is not on "the other store". Props to GOG for making it available.

In that case:

Sam & Max Hit the Road
Simon The Sorcerer 1 & 2
Journeyman Project 2 & 3

[ These games look amazing!

Course they are! Back in the day, rumor had been that Midway halted MK production, in order to devote itself and its resources, on "Suffering: Prison is Hell"! Lots of gore, original "horror" (the creatures were designed by a recently deceased old Gramps who designed creatures for movies on the big screen), enough ammo to let you aggressive approach to anything that moves, special tactics (different weapons have different effect on different creatures), enemy hate other species (for example slayers shiv junkies and vice versa), hidden rooms, secret weapons and great npcs, with convincing voice acting! Best thing is the monster transformation (in 2nd game it is expanded, 3 different monsters with different attacks exist), the multiple endings (neutral, good, evil), the morality decisions and that npcs act like coop players in places! Stationary guns are a great extra. All in all, it is the real deal!

Only problem is that the sequel, forbids you from carrying healing items (they are only for stationary use) and you can only have 2 different weapons on you at anytime; this is a real catastrophe.

I would say Beneath a Steel Sky is a must have...
...literally.

I have ran and completed Bloodrayne on a Windows 10 pc.

^This

Plus Ultima 7 and System Shock 2

Definitelly two WH40k turn-based strategies:

WH40k: Chaos Gate
WH40k: Rites of War

Both are situated in vastly different scale.

Rites of War is rather "strategy-scale", a bit similar to Panzer General 2, but in my opinion far more friendly for beginners (so even if you don't have too much experience with this genre, you can still try Rites of War), and those big sprites of units are so juicy!

Chaos Gate, on the other hand, is rather more into "tactic-level", with single space marines, occasionaly some vehicles (and of course you can develop your every soldier, give new equipment etc.)

So I'm guessing that depending on your preferences, at least one of those will bring you a lot of fun (I personally enjoyed both, but a bit better Rites of War)

Speaking about turn-based strategies/tactic game - I highly recommend Incubation from this pack

I've never played in any of those Battle Isle "classics", but Incubation is top notch - yeah, the models of characters are very ugly, but other than that - it's juicy, but quite challenging title.

Oh yes, History Line 1914-18 is awesome!

My "one" game would be backyard baseball, not specfic about which one, just having one on here would be nice, and next to RCT1 in my library I'd have the two games from childhood PC gaming.

Other then that I'd like to see some konami releases on GOG, silent hill 1-4 DRM free that starts with a click would be some great niche titles for GOG to have but its asking for the impossible. Other then that perhaps try to influence publishers of DS/PSP/vita games to release on PC through GOG, its a hidden gold mine there and I dont think they'd be too upset about DRM free versions of older games.

I'd love to see any of the backyard games here.

Too bad not many folks seem interested in them.