Ropes

They are probly either too heavy, or dont have enough slack.

I don't think they do that (do they?). Don't they only move with phys_explosions, or with phys objects that they are parented to?

I tried it with more slack, more distance between the end points, env_physexplosion and env_physimpact. No dice.

I think strider is right..
The only case a rope would move, is if you tie a physbox or similar to it.

The move_rope and keyframe_rope entities need to be shaken to get the cables to move.

Take a look at the sdk_cables.vmf example map. Maybe you can set a physbox near the cables or parent the physbox to an anchor point, detect damage to the box (an OnDamaged output) and trigger movement in the anchor points.

The move_rope and keyframe_rope entities need to be shaken to get the cables to move.

Take a look at the sdk_cables.vmf example map. Maybe you can set a physbox near the cables or parent the physbox to an anchor point, detect damage to the box (an OnDamaged output) and trigger movement in the anchor points.

Take a look at the Example Map vault for Cable Shakes. Hope it helps.