Starcraft AI blog

SAIDA introduces new drop skills in TvT. Bots have not faced drops like this before, and are not adept at defending. SAIDA likes to drop tanks and goliaths with several ships, at the edge of the map, using your mineral line or your buildings for cover. The drops are able to destroy a base if the defender is weak or disorganized.

There are a lot of defensive possibilities; I’ll list some. Make SAIDA pay for those drops!

active defense

• Drop prediction. If you spot moving dropships, you may be able to guess where they are going. You can try to divert wraiths or goliaths to intercept the path, or send defenders to the predicted drop zone.

• Wraiths. Seek out those dropships and make them hurt. If they’re loaded, you can force them to unload prematurely. If the drop already happened, shoot down as many as you can. Even if the dropships escape to friendly territory, you have caused delays and gained time.

• Counter drops. Drop your own units directly on top of the enemy units. SAIDA’s tanks will have to unsiege, and (if you have coordination skills) you can take the opportunity to move in with other units. A good counter drop can turn the enemy drop from a benefit into a cost.

• If all else fails, maneuver tanks to pin down and destroy the dropped units. Don’t let them stay alive and kill more of your stuff. So far, Tscmoo has done the best job of this.

exploit predictability

Bots tend to have stereotyped play. SAIDA likes to fly along the edge of the map and drop on the edge where its units cannot be surrounded. An opponent could record the events, notice the obvious pattern, and prepare special defenses. Or at least: Once you’ve seen dropships, set up some turrets to see them coming and restrict their movement. By the time big drops can happen, terran commonly has excess minerals and can afford to throw up a bunch of turrets even if they aren’t efficiently placed.

• Place turrets along the edge where SAIDA may approach. (This is more common in TvP as defense against arbiter recall.) If you have high confidence, you could even detail goliaths to lie in ambush. If SAIDA doesn’t know about the turrets, it will have to fly into range and take damage before it can evade. At worst, you will have seen the drop and can try to predict where it will go next.

• Lay spider mines in potential drop zones, such as behind your mineral line. I don’t know whether SAIDA will drop on the mines and blow up, or scan the mines and drop elsewhere, but it’s to your advantage either way. Laying mines near your mineral line is not as clever against protoss or zerg drops, because protoss and zerg can more easily drag the mines into your workers. Terran doesn’t have a good unit to drag mines with.

stay alive

• Lift the command center and run SCVs. There’s a good chance you can keep the CC alive and quickly restore the base to operation once the drop is cleared. Lifting the command center is a basic terran skill; I find it surprising that Krasi0 doesn’t have it yet.