Forge is one big collaboration with people from different countries and languages. All of these people are united in their love for Magic: The Gathering. I am guessing that Forge has had at least 100 people submit Java code to the project and at least 50 have made substantial contributions.
I presume most people add a card or two that they really wanted. Forge is a random collection of cards, so you can never be sure which cards Forge has or doesn’t have. Most people also have a favorite card, or three, or a card that they enjoy using. Even if the card is usually crappy but has the chance to win the game once in a while. Crappy cards aren’t crappy 100% of the time, so it is ok for Forge to incorporate them.
Forge also does not have forum flame wars. Everybody acts like an adult (which is rare of the internet) and avoids the usual, “I’m right and you’re wrong” arguments that are never ending. This subject reminds me of an old joke about two guys who both moved. One guy says, “My new neighbors are nice but my old neighbors were nice also.” The other guy says, “I hate my new neighbors because they are just like my old neighbors.” Basically if you are nice, people will respond nicely and vice versa if you are angry.
All open source software is a testament to cooperation and the joy of working with your fellow man. Other types of media such as books and movies do not lend themselves to collaboration as well as software (for whatever reason). And many types of open source projects are not videogames. Maybe amateur videogames tend to be not very good or maybe open source videogames need more of a singular vision to be successful, who knows?
I am still surprised that people want to work on Forge because it was started by an amateur programmer using an old PC. Truthfully I started Forge because it was cheaper for me to code new cards versus buying them and I still get a thrill when I use rares like Darksteel Colossus, Elvish Piper, and Wrath of God because I never owned them in real life.
I am also happy that Forge’s simple AI does not detract from the fun factor. Making that early decision was a tough one.