The 17-year-old boy identified as Rustam, who had broken his leg and was bored, saw his character die on screen before he passed away at his home.
The tragic death happened in the town of Uchaly in southern Russia's Republic of Bashkortostan.
The boy was hospitalised late last month after losing consciousness. Following a leg injury, the boy had been homebound since August 8, seemingly with limited adult supervision, state-run TASS news agency reported.
He had been playing the game Defence of the Ancients almost continuously, only stopping to sleep and eat.
It is a schedule which works out at around six-and-a-half hours a day, culminating in the intensive almost non-stop sessions over 22 days leading to his death.
"In the last 22 days it is suspected he played the game almost all the time, stopping only to take a nap and grab a snack. Since August 8 he had a broken leg and has spent all his time at home playing computer games," Svetlana Abramova, a police spokeswoman, was quoted as saying.
Court-appointed medical examiners were looking into the exact death cause, the report said.
Doctors believe he could have died from second class syndrome, thrombosis from not moving around, as on a cramped long haul flight, British daily Mirror reported.
Children's rights ombudsman Pavel Astakhov called the incident "a grave warning to all parents".
"Dear parents, pay attention to your children! Don't let them become hostages to their computer, the Internet, games!" Astakhov tweeted.
In March this year, a 23-year-old Chinese gamer died after spending 19 consecutive hours playing World of Warcraft in a Shanghai Internet cafe.
