I drained my bank into the area of effect placement on each attempt; my final strategy was a crossbeam of mushrooms alongside a diagonal pair of shooters. I'll refrain from echoing a common complaint of speed, although I did agree to the point of naturally avoiding the slowness effect, since most creatures moved slowly enough to be entirely killed in the area of effect. Although I find myself to be an easy target for voice acting and voice-activated sound design, the latter is much harder to do well perhaps due to forgetting the intrinsic nature of most languages to create audible contrasts, and as a result the fun of the voice turns to strife.
The game is a high pressure environment that turns its events on a dime, from a sluggish beater against beetles to a mazer race through the beetles' bullets for that fruitful spoil. Purchasing upgrades or even just healing for the tank could be a novel dimension that allows more disengagement with the Grain mood and further towards the Nerve aspects.
Rock On! Island is a fascinating member in the UFO 50 Collection, particularly for such an unexpected balance towards upgrading the player character rather than building up "towers" with which to "defense." The late game becomes extremely tightly wound, which to my knowledge is greatly inspired by the Bloons TD style, but the absence of that games player character results in a more singular mood of gameplay.