Oleg is the third boss enemy the player will encounter in the game. He is an old man. Early in the game he chases the player just before the player encounters a drawbridge into Tesla Tower.
As a boss
Before the battle he is shown tinkering with the electrical circuiting. A close encounter (or a direct hit by the Teslastaff after rencountering him) will trigger the battle.
Upon first noticing the player, Oleg will chase them across the room, climbing up the ledges until he passes the bottom centre of the room. Upon passing it, he will pull a switch activating some lights and seal himself in the now revealed blast room. Then, he picks up his gun and phase 1 begins.
The first phase consists of Oleg shooting red projectiles from his gun. They will bounce off walls and will kill the player upon contact. However, the player can utilise their polarity cloak to repel the projectiles away from them. The aim of this phase is to reach the top of the room and activate the centre switch. This will unlock the two other switches, which when activated will unlock the corresponding blast door. The player then either needs to wait till a projectile hits Oleg or direct one into him. After hitting him, he will be electrocuted and chase you again, until he passes the centre for a second time. This triggers phase 2.
During this phase, Oleg fires blue projectiles instead of red ones. Some of these projectiles are too big to be reliably repelled and must be avoided. On top of this, two red volt walkers are summoned on the top floor of the room, and if touched will attract the projectiles to the player. The player must avoid them and repeat what they did during phase 1. If they have the teslastaff and are replaying the boss, they can temporarily destroy the volt walkers for some time off. However, during this phase Oleg activates electricity that prevents the player from getting too close to Oleg, meaning they must direct the projectiles better than before. After hitting him a second time, he will be electrocuted again and chase you one last time. Then, upon passing the centre yet again, the final phase (phase 3) will begin.
PC AND CONSOLE: This is where things get really hectic. Oleg will randomly fire red and blue projectiles and there is no way of telling which one he will fire. Two red and two blue volt walkers will now be summoned making dodging the projectiles almost impossible. The electricity remains and the player must repeat what they did for phase 1 and 2. Upon hitting Oleg for the third and final time, he will be electrocuted and fall through the floor into a theatre, opening your escape.
MOBILE: This is the biggest change in the game. On mobile, there is no third phase as it would be too hard for the controls. Instead, Oleg is defeated after phase 2.