LogFAQs > #970332424

Turtling while you establish a strong economy and build a super army is a very reliable strategy in single player SC1 and SC2. The AI tends to have unlimited resources and/or scripted reinforcements, so there's little benefit to harassing. Sometime missions will have a time pressure that forces you to move out and be proactive at various points, but the goal is still to put together a single mass of units that can kill smaller groups very efficiently and then to keep making it stronger until it reaches critical mass.