A fun open source game engine project we've not covered here before is OpenTESArena, an open source re-implementation of The Elder Scrolls: Arena and it just had a new release.
Inspired by other similar projects like OpenXcom and OpenMW, their aim is to have a clean and cross-platform version using the original assets which you can get free from Bethesda. A few days ago a new release was put out to include Wilderness generation, Wilderness automap, City <-> wilderness transitions via city gate, City placeholder in wilderness, Player position in wilderness displayed with F2, CD version support and initial work on inventory slots.
You can see a video about the latest update below:
As you can see it appears to be coming along nicely. Still a large number of features to implement before it's playable enough to be really enjoyable but it's another impressive open source project to keep an eye on. One I will also be following a little more closely now to keep you updated on progress.
See more about it on GitHub.
Hat tip to testman.