The Wall is far from lifeless. In its shadows lurk zyrex — dangerous creatures that attack your colony again and again, testing its defences, your organisation and your ability to respond. Strengthen your defences, secure vulnerable areas, and decide how much you can afford to invest in protection.
Alawar has not published a formal bestiary, but the achievement names in the Steam data identify three distinct zyrex targets by their internal names, and they are the clearest available window into the enemy design:
The general kill-count achievements run in stages — 50, 150, 300 and 600 zyrex killed — which suggests the enemy volume ramps sharply as a colony matures.
Defensive structures are a build category in their own right, and the June demo patch explicitly rebalanced them, making the concrete defence wall cheaper to build. The Russian-language launch announcement adds detail that the English store page omits: base defence requires defensive guns, reinforcing concrete walls, and repairing damaged buildings during the attack itself, rather than between waves.
Community guides describe the defence layer as covering several engagement ranges — long-range turrets, mid-range automated weapons, close-range weapons, rapid-fire options, traps and barricades, plus dedicated anti-armour and area-of-effect weapons for heavy zyrex. Alawar has not published a formal weapon roster, so treat the specific names as community terminology rather than official item names. What the achievements do confirm is that a heavy zyrex exists that needs the anti-armour answer, since a single named achievement tracks killing the Queen.
The zyrex are not the only thing trying to kill you. Emergency events — accidents, disasters and environmental hazards — do not destroy the colony instantly, but they disrupt its operations and trigger cascading problems. The launch coverage specifically names acid rain alongside food shortages, accidents and overpopulation as triggers for unrest. If the power fails 20 times, you have that achievement; the colony is expected to fail, sometimes, and the game wants you building through it.
There is a side quest dedicated to the first zyrex attack, which confirms that the first raid is a scripted story beat rather than just the opening difficulty spike.