Energon drones are cockroach-like non-sentient robots either created or corrupted by the All Spark.
Transformers The Game
When Bumblebee infiltrated the Sector Seven base within Hoover Dam and managed to release the locks on the All Spark, stray energy bolts began to leap from the cube as it slowly shrank, creating a swarm of Energon drones. Bumblebee was forced to defend himself against the critters... and Sector Seven artillery... and a defrosting Megatron! Oy!
Escaping with the All Spark, as Bumblebee drove through Mission City with the cube in his backseat, it radiated Energon in massive amounts, which coursed through the Energon drones which were standing around on the sidewalk for no apparent reason. The drones followed and swarmed Bumblebee, who crashed into a building and had to be saved by Ironhide. While the Energon drones were small, weak, and only armed with a single machine gun, they came in great numbers. Ironhide won anyway.
Another group of Energon drones also attacked Scorponok in a nearby park, but were destroyed.
As Bumblebee retrieved the AllSpark from the Dam, the Cube sent out bolts of energy that turned whatever they hit into Energon Drones. To defend itself. From being saved. Yeah.
Best ignored, the safest thing to do was just grab the cube and run like hell before the mini Scorponoks caught up with 'Bee.
When attacked, the smaller robots will explode and damage anything nearby, and if a larger Transformer is close enough, he'll be thrown back by the explosion.
Later, in the mission "End Game", Megatron demonstrates the ability to control the AllSpark drones. The Decepticon leader has them attack Optimus, while that unimportant rookie proceeds to knock the AllSpark out of Megatron's grasp.
Posessing the AllSpark, Starscream has the ability to create and control Energon drones (here called Spark Drones) and sends waves of them after Create-A-Bot. However, being weak, small, and made of rusted out old vehicles, they easily fall to Create-A-Bot's blaster.
They later appear in both Autobots and Decepticons in a challenge mission, "Drone Extermination".