The game allows players to simulate a Mars landing, or explore the surface (in real time or accelerated time), using the various filters the real-life explorers have (infrared, UV, and so on). Or, in one case, spawn a SUV with howitzers on the roof and blow stuff up; the game is completely mod-friendly and in fact encouraged.
Take On Mars will be available on Steam Early Access on the 1st August 2013, but no release date has been announced yet.
Bohemia Interactive, which also owns the Take On Helicopters license, has released a gameplay trailer showing off what the game is like. Check it out in the video below.