Colony Siege

My instinct when I see 'tower defense plus RTS' on a store page is skepticism, because that genre mashup usually means one side is doing all the work while the other coasts. Colony Siege earned my attention by making both halves feel load-bearing. The core loop puts you in command of a player-piloted command ship that zips around each map constructing towers, repairing damaged structures, and directly engaging the alien waves when the perimeter starts to buckle. That commander unit alone separates this from passive tower-placement games, since every decision about where you fly has an opportunity cost. The strategic layer is built around two distinct enemy factions. The biomechanical Xenos hit in swarms, behave like insect waves, and can clone individual units to punish under-defended chokepoints. The Riven, corrupted former humans, play more methodically and require you to rethink maze layouts that worked perfectly in the previous mission. With 44 distinct enemy types spread across those two factions, you are regularly auditing your tower composition rather than copy-pasting the same build. Defensive towers auto-generate laser fences when placed near each other, so wall-building has a spatial logic to it that rewards tight placement without demanding pixel precision. Spring traps and shockwave emitters add a physics dimension: correctly funneling enemies into lava flows or off map edges feels genuinely satisfying when the routing works out. Between missions you navigate a branching star map, spend earned currency in a persistent shop, and unlock new towers, trap types, mechs, tanks, and strike abilities (air, missile, and orbital). The upgrade tree is not especially deep, but it is wide enough to support different approaches per run. Mission-specific hazards keep the campaign varied: one map has a mining laser as a free environmental kill zone; another uses ice terrain to slow enemy pathing in your favor. Bonus objectives per mission add extra cash incentives if you plan ahead on the mission select screen, which is the kind of detail that rewards players who read tooltips rather than skip them. Post-campaign, Endless mode scales rewards the longer you survive, while Survival mode shifts the threat model by enabling attacks from multiple directions simultaneously, hammering your units and towers more than your base structures. For two-player online co-op, the entire campaign is available from mission one, not gated behind a separate mode. That is worth noting because co-op campaigns in this genre often feel like a second-class feature. The main weaknesses are real. The tutorial and in-mission objective guidance can be ambiguous: at least one reviewer noted a repair objective with no clear prompt, discovered only by clicking around. Voice acting in cutscenes sits somewhere in the late-nineties production tier, which is either charming or distracting depending on your tolerance. The branching mission and tech trees are present but neither goes especially deep, so late-game players chasing systemic complexity may find the ceiling lower than they hoped. Steam player counts have been quiet since 2023, so finding a live co-op partner outside a friend group is not guaranteed. If you have a co-op partner lined up and a taste for hybrid strategy that demands active management rather than static tower placement, Colony Siege delivers a surprisingly complete package from a solo indie studio. Solo players focused on pure mechanical depth or a rich modding ecosystem should temper expectations, but the core design is solid and the Steam community verdict, sitting at Very Positive across its review window, is not wrong.

Diego · Scout Team

Strategy & simulation

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