Evaluate the first element on the stack. If True, then execute statements that follow, up to the endif or else statement. If False, execution skips to the first statement following the endif or else statement. Any nonzero value is consierered True, a value of zero is False.

# Creates a runner at the units current coordinates 
# every three seconds, but only if there is digitalis underneath. 
CurrentCoords GetDigitalis if 
	CurrentCoords 2 10 20 CreateRunner 
	90 Delay 
	endif

# Pick a random integer between 0(inclusive) and 100(exclusive).
# If the random number is less than 95 emit 10 Creeper,
# otherwise emit 100 Creeper.
0 100 RandInt 95 lt if 
		CurrentCoords 10 AddCreeper 
	else 
		CurrentCoords 100 AddCreeper 
	endif