- Demonic Spiders: The Skimmers in Creeper World 4 are the bane of most players. It isn't bad enough that they glide at speed over terrain and across the void to explode on your towers, drenching them with Creeper, nor that they take two sniper shots to defeat, nor even that most Skimmer nests can release two at a time. Each time you destroy one, its crystal shard will be flung away and explode, releasing an EMP that can stun any unit it touches. Crystal shards keep their momentum, so it will most likely sail into the midst of your defensive lines and take out half your weapons including six cannons, both your snipers and that one ERNed mortar you were pinning your entire strategy on, leaving you to watch helplessly as the Creeper oozes on over and your defenceless mortar suffers a slow, agonising death.
- That One Level: Farbor in the third installment. All levels up until this one can be won through a strategy of "Build up an impregnable creeper/spore-proof fortress before moving on to the main objectives", but Farbor is a Timed Mission which can't be won this way.
YMMV / Creeper World