The ‘Turtle’ strategy is a purely defensive operation, where all your production and units are focused on ‘entrenching’ yourself near or around your base and holding your ground; creating a high density of strong units to protect against attacks from your opposition.
If you know your units, you’ll be aware that some are ‘soft’ counters and some are ‘hard’ ones. This means certain units will deliver more damage to another type of unit, and are build for a specific task. For example, Wolverine is an anti air unit, and a hard counter to anything that flies, but a soft counter to anything else.
I play mostly 3v3 now, and Fort Deen is one my my favourite maps to play as one of my favourite leaders: Captain Cutter. Why? – Fort Deen is very much a Turtler’s heaven, the energy barriers provide impassable and highly defendable routes; the middle valley and the smaller bottleneck valleys just invite you to sit some counter units there and wait for a war.