At an EU competitions hearing, Microsoft defended its plan to acquire Activision Blizzard, the company behind Candy Crush and Call of Duty.
According to Microsoft, the $68.7 billion (£56.8 billion) agreement will give more gamers more options.
Rival Sony, which was present at the hearing, claims that the merger would give Microsoft excessive control over some of the most well-known video games in the world. .
A significant competitor to Microsoft's Xbox gaming console is Sony's PlayStation.
Tuesday's EU hearing, according to Microsoft President Brad Smith, was "an important day.".
He also dismissed Sony's worries that if the merger goes through, Xbox users might only be able to play Call of Duty and other Activision Blizzard games.
After the hearing, he said, "This has never been about spending $69 billion so we could buy games like Call of Duty and make them less accessible.
"That's not a great way to create a $69 billion asset that will increase in value over time. ".
Activision Blizzard released the following statement: "We are confident regulators will find that our proposed merger will enhance competition, create more opportunities for employees, and produce better games for our players. ".
Although the hearing was private and not available to the public or press, it was also rumored that chip designer Nvidia and Google were present.
Microsoft and Nvidia have announced a partnership that will make Activision Blizzard and Xbox PC games accessible through GeForce Now, Nvidia's cloud-streaming service.
The tech company needs to persuade regulators all over the world that the deal, which is the biggest in gaming history, won't hurt its rivals.
It has already received approval from some nations, including Saudi Arabia, Chile, and Brazil.
Although it has not yet made a final decision, the UK's competition watchdog recently declared its opposition to the deal, and the European Commission commissioned an investigation.
The UK Competition and Markets Authority has suggested that Call of Duty might be sold separately.
Sony has so far rejected Microsoft's offer to make all current Activision Blizzard games available on Nintendo, Sony, and Steam for at least the next ten years.
The company has previously acquired game developers like Fallout creator Bethesda and Minecraft creator Mojang. The new Bethesda game Starfield will initially be an Xbox exclusive when it launches, as it has already been announced.