Crawler

The Crawler is a Tier 1 ground kamikaze unit that moves toward enemy targets and self-destructs, dealing area damage on death. It is produced from the Ground Factory (previously produced in a dedicated Crawler Mech Factory in older builds) and functions as an expendable shock unit: it is inexpensive to mass-produce and is intended to detonate inside enemy lines to damage buildings, units, and cores.

Crawlers have moderate health for a T1 disposable unit and are specifically designed to kill themselves when their explosion triggers; their attack is implemented as an instant AoE "death weapon" that activates on death. The explosion deals 80 area damage over approximately 5.5 tiles in current listed stats. The unit no longer detonates automatically on conveyors (a behavior that was changed in earlier updates). Over multiple updates its health and explosion radius have been tuned: health rose and fell across versions (notably increases to 180 and 200 in older builds before later reductions), and area damage has been adjusted between builds. The Crawler’s speed is represented as 7.5 tiles/second in later builds. The unit’s research historically used Coal and Silicon; a notable update drastically reduced their research cost (Coal: 400 → 4, Silicon: 600 → 6 in a listed patch).

In combat, Crawlers are effective in large numbers because each explosion can damage multiple structures and units. They do not apply damage over time and cannot pierce walls; cheap expendable blocks like Junctions or small Copper Walls can be used to force premature detonation. Massed Crawlers are vulnerable to long-range splash and instant-kill defenses: turrets such as Ripple and Arc can destroy Crawlers before they reach valuable targets, and splash defenses can cause them to detonate away from high-value structures. Crawlers will always explode and deal their death damage on death; internally, the explosion is implemented by the unit firing an instant-despawn bullet that applies the AoE effect.

Practical uses and counterplay:

• Offensively, Crawlers are best used in swarms to overwhelm static defenses and to destroy production buildings and enemy cores when launched en masse. They are a cost-effective option on sand-heavy maps because Crawlers and Flares (and their Tier 2 upgrades) can be produced using only sand-derived resources when Coal can be generated by Spore Pods and Oil.
• Defensively, place sacrificial breaklines of cheap blocks (for example, a line of small Copper Walls several tiles in front of your main defenses) to cause Crawlers to detonate prematurely and reduce damage to core structures. These lines are easy to repair and also work against player-directed Crawlers.
• Turrets with high single-target damage or quick targeting such as Arc and long-range splash turrets like Ripple are effective counters; Scatter-type turrets hard-counter Flares more than Crawlers because Crawlers are ground-targeting and less easily spammed by defenses.
• In PvP, mass-production of Crawlers via schematics on sand-dominant maps can produce a powerful, low-effort army capable of crippling enemy production if not adequately defended against.

Trivia and implementation notes: the explosion is technically implemented in the game code as a bullet that instantly despawns after spawning to produce the AoE effect. Crawlers are unique among units for historically requiring Coal in their research and for being the only unit that uses Coal as a research requirement in some documented builds. They appear in fan works (such as Animdustry) with mechanics themed on their explosive behavior.