I sweep the lower decks with the shotgun, dropping a bomb at every choke so the wave thins out before the siren peaks.
Holding the arrow keys on a diagonal keeps me ahead of the radiation spikes; once the counter calms, I swap weapons and plant the next charge.
Unlocking the extra firearm early pays off - Ctrl sprays whatever survives the blast while the bomb timer resets.
Space first, Ctrl second: I bomb the lab doors, roll back, then finish stragglers before the radiation meter jumps again.
Slot three stays reserved for the heavy weapon; the lingering damage keeps mutants from slipping away after a detonation.
FlashGamesBox lets me rerun routes in any browser until every bomb chain melts the next mutated wave on schedule.