They are both in some way related to The Elder Scrolls III: Morrowind
OpenMW is an open source game engine that can be used to play Morrowind. (There is an unfinished “Example Suite”, a CC0 licensed game data that can be used instead of Morrowind game data, so technically OpenMW does not play just Morrowind. Feel free to come help finish the Example Suite)
Skywind is remake / reimagining of Morrowind game in a modified Skyrim engine.

Isn’t Mattermost basically open source Slack?

Oh, this video by Digital Foundry is also relevant:
Hands-On With Steam Machine: Valve’s Beautiful PC/Console - Specs, Impressions And More
https://www.youtube.com/watch?v=2rv83LgXiN0

There are many graphics settings that you can configure. So you can play around until you get just right performance for the FOV that you want to have.

Cool, but the Newerth-related games that I care about are the Savage series.

(from Hot Shots! Part Deux)

There is a project called Example Suite, which is meant to be a CC0 template for building other games upon it.
But I am not aware of any other from-scratch games made for OpenMW. There are quite a few total conversions, but those all use some of Morrowind game files.

Selling Skyrim yet agan would be too much. Todd said that they need to go for something less obvious this time.

lol, Todd sold you Oblivion again

All right, good stuff.
But I’m slowly getting a feeling that there are quite a few “European alternatives” websites right now.
Will make a list of them once I have time.