After the paid Skyrim mods fiasco I didn't expect Valve would be back so soon with a new implementation, nor that it would be a genuinely good one.
Valve's latest answer to the age old problem of how to support custom game developers is the Custom Game Pass, an in-game purchasable item that grants you additional content or features in select custom games within Dota 2. Here's how it works:
Each Custom Game Pass will remain active for 30 days and work only for the custom game you selected. In return your patronage you will receive a few bonus features, and potentially cosmetic items, in order to make your life slightly easier, and your character more than slightly cooler. What it won't offer is anything that might influence the balance or ruin the gameplay experience for the holder, or anyone else that might be in the game with them.
The custom games themselves will remain free for everyone, but if you for example buy a Custom Game Pass ($1) for Roshpit Champions you will gain an additional stash and character slot as well as a few other minor perks. By doing so the mod developer will earn 70% of your purchase, with the other 30% going to Valve themselves, which is a completely fair deal.
Roshpit Champions is the first, and currently only, custom game that supports the pass
You might be wondering at this point, what's stopping developers from releasing ridiculously overpowered items for Custom Game Pass buyers in order to rake in some of that sweet, sweet pay-to-win money? The answer, slightly surprising, is that Valve themselves will be curating every single Custom Game Pass in order to ensure that the benefits match the asking price without impacting anyone's enjoyment.
Finally, if you do end up buying a Custom Game Pass only to learn that the mod developer is a bit of a prick, or that the pass simply doesn't offer you any value, you can easily request a full refund as long as its done within 48 hours of buying the pass.
And there you have it, all the important information about the Custom Game Pass. While I was initially suspicious when I started reading the announcement I have to commend Valve on their efforts as this Custom Game Pass system appears to be a flawless one, provided their moderation team ensures a certain level of quality from each and every single pass. Good on ya, Valve!
If you're interested in all of the minute details that I might have missed in the post above, check out the official FAQ.