unit-crawler

The Crawler is a low-tier ground unit that charges toward enemy targets and self-destructs on death, dealing a large area explosion. It is a fragile but inexpensive suicide unit intended to overwhelm structures and units by detonating in close proximity. In-game mechanics treat its explosion as a bullet spawned on death that immediately despawns while applying area damage; the explosion triggers when the Crawler dies and will always occur (including when destroyed by turrets or other units).

Crawlers are produced from the Ground Factory once unlocked and historically have moved between different factories in past updates. They are researched using Coal (notably, the only unit research that uses Coal), and several balance changes over time adjusted their health, speed, and explosion radius — current values from post-update notes show a modest health pool and an explosion dealing around 80 area damage with roughly a 5.5 tile radius. Their movement is straightforward: they move toward enemy targets and detonate on death; they no longer detonate on conveyors as of earlier updates.

Because their sole offensive capability is a single death-triggered blast and they are not durable, Crawlers are typically deployed en masse or used as sacrificial fodder to break through defenses. Practical strategies and interactions include:

• Place cheap sacrificial blocks (e.g., Junctions or small Copper Walls) a few tiles in front of a defensive line to force Crawlers to detonate prematurely and waste their damage on expendable targets. A single line of such blocks roughly 7 squares ahead of your defenses can significantly reduce Crawler effectiveness and is inexpensive to repair.
• Long-range, splash-capable turrets (such as Ripple) and high-DPS turrets that can one-shot Crawlers (like Arc variants) are effective counters because they can destroy Crawlers before they reach critical structures. Splash damage helps detonate groups sooner.
• In PvP, player-controlled Crawlers can be steered to avoid premature detonation and target high-value structures or be detonated selectively; human opponents may therefore use them more effectively than AI, and direct-control detonation allows targeting of specific positions.
• Crawlers cannot pass through fully walled bases; complete walls and narrow choke points deny them access, forcing them to detonate on the outer defenses instead of core targets.
• In campaign and sandbox contexts on sand-heavy maps, Crawlers (and Flares) have the advantage of being producible using only resources available on sand when combined with Coal generation from Spore Pods and Oil production; mass schematics of Crawlers can be an economical way to pressure enemy production in certain map formats.
• Large swarms of Crawlers are countered similarly to other Tier 1 swarms: prioritize area denial and splash defense, and rely on turrets that extend engagement range so Crawlers explode prematurely.

Notes from development history and quirks: earlier builds changed their factory, command limits, speed units, and damage/health numbers multiple times. The explosion behavior is implemented as an instantaneous bullet spawn on death in the code, and Crawlers always trigger their death explosion. They have seen adjustments to prevent issues like failing to detonate on Cores and to balance their production cost.