PHILADELPHIA — Jenna Papagni stood amid a crowd of hundreds outside the Wells Fargo Center on Sunday. She was at the Philadelphia arena for the Overwatch League Grand Finals, an annual e-sports tournament, and she came dressed for battle.

“This game is my life,” said Ms. Papagni, a 20-year-old from Newark who was dressed as D.Va, an Overwatch character who fights in a mechanical exoskeleton.

The league is modeled after traditional sports, with teams in 20 cities on three continents competing in a seven-month season that was drawing to its conclusion.

Like many of the 12,000 fans who converged at the sold-out tournament to see the San Francisco Shock take on the Vancouver Titans, Ms. Papagni was drawn to the game because of its inclusionary nature and ease of entry.