If you've been paying any amount of attention to Team Fortress 2, you've probably noticed that it's home to some of Valve's wackier ideas. The company says it may not have started as a test bed, but it's certainly become one as it's used to experiment with new strategies.

"In the end, TF2 has been ended up being one of the most useful tools we've ever built to reduce risk in our company's future," lead designer Robin Walker said.

"It's been really nice that it's also brought in significant revenue throughout that time, but ultimately, the importance we place on understanding our business and our customers has made it totally worthwhile." Walker told Gamasutra that without TF2, Valve's lack of experience in monetization would be "terrifying."

He says the hidden goal for TF2 was to explore ideas that "were potentially a requirement for the long-term survival of the company." When the game first came out, it appeared that MMOs were going to take over the market, so Valve started building persistent items. When the free-to-play market rose, it used TF2 as a test bed for microtransactions. The gambles seem to be paying off, as the game continues to evolve and remain popular.