GOG is 10 years old and is giving away Shadow Warrior 2. If you're interested in such things, there's also an history of GOG page. If you're looking for games on discount, there are a few "10 anniversary collections": Shadow Tactics, Theme Hospital, Homeworld Remastered, System Shock 2, Dungeon Keeper 2, Kingdom Come Deliverance, etc.
The GOG summer sale goes on and there's another giveaway. The first one was Xenonauts about a week ago. Now GOG is giving away Ziggurat... for free, yes. The GOG Summer Sale ends on June 18 so there's still time to buy games. Here's a few retro titles on sale: Zork, Star Wars Galactic Battlegrounds, Knights of the Old Republic, Close ...
This time the GOG weekly sale offers a mix of new old-school games of different genres: Pizza Connection, King of Dragon Pass, Frozen Synapse, River City Ransom, Flatout, Sacred Gold, Darkstar One, Ghost Master, Patrician 3, the Blake Stone series and more...
Lots of games on sale as usual. This time you can also buy Leprechaut Hats (!). Every hat is a mystery game: you don't know what you're buying. Last time I bought something like that I got a game for children. Should I try again?
Every year there's a winter sale: Steam winter sale, GOG winter sale, everything else winter sale. If you didn't spend all of your money during the Black Friday sales, you can do it now. The GOG winter sale is about to end, but the Steam sale has just begun.
Black Friday is coming and lots of games on GOG are on sale at very low prices: The Witcher, X-Com, Anvil of Dawn, The Settlers 2, Theme Hospital, Titan Quest, Heroes of Might and Magic, Wing Commander, Ultima, Tomb Raider and many more. Also: MDK is free, go and get it.