For a while now our devs have been getting e-mails from G2A with proposals to work together. We no longer actively jump on additional distribution opportunities (there's a new bundle every day...), but the whole G2A subject needs to be talked about a bit more.
Before I dive deeper, it's important to understand what G2A is and how it works. You may have seen the occasional reddit thread with their G2A Shield deactivation experience, and probably saw tons of streamers and youtubers endorsing the company due to their affiliate program.
In short, G2A is like Ebay for game keys.
The basic idea is a novel one - with the abundance of game keys spread through bundles, odds are you'd want to sell off keys for games you don't really want, and make a few bucks when doing so.
So it's pretty simple for sellers:
Get a game key from a bundle
Sell it on G2A
Make a couple of dollars
Meanwhile the consumers get a really good price on games.
The problem is that this business model is fundamentally flawed and facilitates a black market economy. I've spoken to a merchant on G2A about how he's making $3-4k a month, and he outlined the core business model:
Get ahold of a database of stolen credit cards on the darkweb
Go to a bundle/3rd party key reseller and buy a ton of game keys
Put them up onto G2A and sell them at half the retail price
I've reached out to distribution partners inquiring about the amounts of chargebacks happening, and it's killing some of them. [article on indiegamestand]. There are variations on this business model, as some "merchants" live off bots who actively scavenge keys from Twitter/Twitch/Facebook, and then use Steam's gifting feature to "sell" the key on G2A.
tl;dr websites like G2A are facilitating a fraud-fueled economy where key resellers are being hit with tons of stolen credit card transactions and these websites are now growing rapidly due to low pricing of game keys

The financial impact is actually huge
I've been dismissing the issue for a long time. Sure, a few game keys leak here and there - nothing major. For a few months we supported our own little store on tinyBuild.com - just so we can give some discounts to our fans, and do creative giveaways that'd include scavenging for codes.
The shop collapsed when we started to get hit by chargebacks. I'd start seeing thousands of transactions, and our payment provider would shut us down within days. Moments later you'd see G2A being populated by cheap keys of games we had just sold on our shop.
Coincidentally, this is when we were having discussions about partnering up with G2A and how that'd work. I really wanted to find out what kind of financial impact this marketplace can have, and after asking for sales stats in 3 separate discussions, I finally have them.
From the e-mail:
SpeedRunners Early Access Global: 24,517 units sold with an average price of €6.26 per unit.
Punch Club Global: 1,251 units sold with an average price of €8.72 per unit.
Party Hard Global: 890 units sold with an average price of €7.95 per unit.
If I do some simple calculations, it comes down to this:
G2A Pricing
price | copies | sum | price | copies | sum |
Punch Club | 8.72 | 1251 | 10,908.72 | 9.99 | 1251 |
Party Hard | 7.95 | 890 | 7,075.50 | 12.89 | 890 |
SpeedRunners | 6.26 | 24517 | 153,476.42 | 14.99 | 24517 |
total EUR | 171,460.64 | total EUR | 391,479.42 |
The total value of these transactions on G2A was ~$200k