TL;DR – A DLC that is full of exciting ideas but also some missed opportunities and frustrations.
Disclosure – I paid for this DLC

Surviving Mars: Below and Beyond Review –
Over the years, one of the games I come back to once in a while has been Surviving Mars. This is a strategy game/ city builder about constructing the first human colony on Mars with drones, domes, and danger, oh my. While it was full of promise, it hit its stride with the Green Planet DLC, allowing you to terraform Mars into an oasis gradually. For a long time, this looked like it would be the final stop for the game, but recently there was a surprise announcement of a new DLC Below and Beyond, which we will look at today.
The essential overview of this new DLC is that while exploring the surface of Mars, you have come across these vents under the surface. Here there are large tunnels, old lava tubes, so large that you could both explore and even colonise them. The one big drawback is that they are very dangerous as cave falls can crush rovers and cut off passageways. You can use technologies found in the new Recon and Expansion tech tree to make exploring safer. Still, if you want to colonise down below, you will need sturdier materials, which is good because it just so happens that several asteroids are coming close to Mars’ orbit with Exotic Minerals just perfect for the new task.