Red Faction Armageddon is a genuinely good Red Faction entry that was unfortunately very hated in it's release, as the fanbase was justifiably attached to the mars of RF Guerilla, and the freedom and systems associated with it. RFA has destruction like in Guerilla, but it's janky. The plasma beam is needed for quick and fun destruction, and be sure to have three or more weapons. Saving place for the hammer AND magnet gun will cost you. The feel is different, and the exploration is linear. It feels like an entirely new dev team made this entry, but in the context of the entire series, RFA returned to the roots, reintroducing elements from the first game. The world building is gorgeous, especially on the surface, where I wish more of the game took place, and invoking joy at the thought of a revisit, but to enjoy the game you must accept the sad, ugly notion of being stuck in dark caverns for most of the game. The caves are well made but have the same issue draugr dungeons in Skyrim have, where you just don't want to be in them. The introduction of new lore that doesn't collide with the previous, an okay story, new and improved techs from the earlier RFG, and taking elements from other third person shooters makes the game refreshing for those who enjoy the TPS genre. The worst part of the game is by far the writing, quips, and execution of the story, though having struggled with this game years ago, none of it bothered me as I slowly floated through the game. Though, on PC, the game is clearly just a port of the console version, and crashes often, with an occasional inability to load a game. You'll just have to restart the game if it happens. Hard difficulty is well paced, not too much but not terribly easy, the end being much more severe, with hordes all around you at most times. Insane difficulty has this severe difficulty affect most of the game, and is thus tedious. Expanding and exploring the underground of Mars, the old Ultor facilities, as well as Marauder and Colonist camps throughout the caverns, RFA devastates Mars' surface and adds a new layer to the world we knew. Though the weather is now uninhabitable, the air is still breathable, so Marauders have also remained on the surface, though most surface Marauders belong to the antagonistic cult of the game. Ignoring the martian threat, an expanding on the Genetic Nanite Research of Ultor, The White Faction, or the conditions and Red Faction of Earth would be the sure move of any sequel.
(SPOILERS)
The ending of the game allows for world building both on a habitable surface and underground, and something along the lines of both games is not an impossibility, with the Martians inferrably eliminated.