Microsoft is founded
Bill Gates and Paul Allen founded Microsoft, the company that would enter gaming with Windows PC titles and, in 2001, launch the Xbox.
Source: Nintendo Wiki — This Day in History: April (nintendo.fandom.com)
The Elder Scrolls Online launches on PC
The Elder Scrolls Online opened its servers on PC and Mac, taking Bethesda's fantasy world into a massively multiplayer Tamriel for the first time.
Source: Game Informer — The Games of April: https://gameinformer.com/b/features/archive/2014/04/21/comparing-this-april-with-recent-years
Persona 5 launches in the West
Persona 5 was released internationally for PlayStation 3 and PlayStation 4, and its stylish Phantom Thieves story made it Atlus's breakout global hit.
Source: Codex Gamicus — April 4: https://gamicus.fandom.com/wiki/April_4
Enjoying the tour? Step inside the full museum — rooms for Nintendo, PlayStation, Xbox and the Arcade, a playable arcade cabinet, the Museum Exam, and the Passport stamp collection.