Rolly is an enemy most frequently found in Agnisort.
Alpha Lore (unlocked by killing Alpha variants)
Rolling-based Generator Unit, built as a mass-producible version of the much more expensive Rollster Beta.
The power-intensive Home Security market takes no prisoners, and every economic advantage a firm can muster is worth keeping close to the chest. It's no surprise that the Corp made a whole mess of these things. They're really great at rolling around, and if not connected to a generator harness, they'll occasionally hop off the ground.
Beta Lore (unlocked by killing Beta variants)
As the rolling apparatus itself only requires kinetic movement on the inside to operate, the construction of the Rolly's internals is much simpler than that of his big brother, and as a result is faster and cheaper to produce. Their resistance to most heat-based hazards made them a great fit for powering the Corp's Superhot facilities. After the entire Superhot facility set was decommissioned for reuse as a Project Site, all existing Rollies were simply set free from their generator harnesses, and allowed to roam wild.
Gamma Lore (unlocked by killing Gamma variants)
After the Superhot decommission, we kept these guys in development mostly because they're fun to watch bounce around, and the Board seems to love that. We built additional models that split into smaller Rollies when destroyed, but we freely admit it was mostly out of a feeling of duty for these poor guys, and not because it served any vital Project function. Research shows most Contractors encountering these advanced models tend to blow them all away at once, anyway.