Among the other design decisions illuminated by the panel: Brevik and his team (who were eventually rechristened Blizzard North) copied XCOM’s “actual tile square basis.” Brevik admitted that Diablo’s design “was basically built upon a screengrab from XCOM.” Also, Brevik was the dev team’s last holdout on two of Diablo’s most iconic elements: real-time control and online multiplayer.

Source: Post-mortem: Ms. Pac-Man, Diablo dissected by their original devs