Julius

Julius is an open source re-implementation of Caesar III. It will stay true to the original while bringing the game to new systems as well as improving the UI and adding support for widescreen resolutions. This version should even be compatible with save files from the original game! As usual, asset files are required to run it, but since the current release is at version 1.0 it should be rather complete.

I found no screenshot from it, but this unofficial video shows the game:

Pioneer

Old-time readers know I like to follow the game Pioneer. There's something massive and cool about this open-ended space game. It was over a year since the last release, so a lot has happened. There's a new mission, new star systems, new ships, new weapons, new music, new sound effects, overhauled icons, a flyby camera view, improved starfield rendering, audio alarms and so very many other things I could go on the rest of this day. (Read the entire changelog here.) There is also a fun option to remove the UI when taking screenshots, something I can imagine will be useful as the game has many breathtaking views.

Indeed a breathtaking view in Pioneer.

Platform Game Engine

The Platform Game Engine project is exactly what it sounds like, a game engine and toolkit for creating platform games. It seems very complete and feature-filled, with an advanced editor with all sorts of tools as well as advanced game features such as warps, doors and world maps. Long story short, if you want to create a platforming game without coding, this might be a good place to start!

Editing backgrounds in The Platform Game Engine.

GearHead 1.310

Roguelike mecha role playing game GearHead is getting a new release while development of GearHead 2 advances alongside it. Several improvements have been made. As an example the game now features thinner, nicer looking walls and there have also been some improvements to the UI. This is a rather unique game that seems to have much thought put into it. A tip is to read the instructions a bit down on this page before starting.

GearHeads title screen. Note the nice pixel spaceships in the background.

Dungeon Crawl Stone Soup 0.23

Dungeon Crawl Stone Soup has been featured here a few times before, and this classic roguelike still keeps up the regular releases. This version has an overhaul of the trap system, refreshed monsters, UI improvements and many other things I'm not sure I fully understand as a non-initiated observer. ;)
 

I really like the log describing what is happening in Dungeon Crawl Stone Soup. Very immersive!

OpenSWE1R

OpenSWE1R is an open source port of Star Wars Episode 1: Racer. This will make it possible to run the game on modern systems and will most likely also support new resolutions and such that the original game didn't. You will still need the original game files though. I have fond memories of playing this on my Dreamcast, so I believe it could be worth a try again.