You can get a free copy until December 30th, 2 PM UTC and it contains the base game plus Worms Revolution - Customization Pack, Worms Revolution - Mars Pack, Worms Revolution: Funfair DLC and Worms Revolution: Medieval Tales DLC. The DRM free version from GOG does not feature online multiplayer, local only.
Other lists of games you might be interested in looking at during their sale includes:
- 2K Games
- Indie Hits (or build your own indie bundle)
- Devolver Digital
- Paradox Interactive
- Star Trek
- Star Wars
- Timeless Classics
The GOG Winter Sale lasts until January 2nd, 2023, 11 PM UTC.