[earenndil]

If an indie game that gets crazily popular is on both your own store and steam, everyone will buy it on steam because they have no incentive to buy it from your store.

[dvt]

Have you read (3)? Contracts would stipulate to only distribute through your platform.

[rhizome]

As far as #3 goes: congratulations, you've invented Nintendo.

[earenndil]

If it's only distributed through your platform then their game won't become crazily popular.