What are your favorite custom games?

Custom games/game modes/rulesets give gamers the ability to enjoy some games nearly infinitely. Gary's Mod, Rust, Minecraft, Robolox, Fortnite, and many others keep people coming back as people create new ways to play.
When I was younger I played a ton of Warcraft 3 custom games. I remember there being a solid ~2 years when that was almost entirely what I would play whenever I was able to use the computer and then another 3-4 years after where I would play at least a couple of times a week.

I remember loving custom games like:

• Defense of the Ancients (DotA)
• Island Troll Tribes (also Jungle Troll Tribes to a lesser extent)
• Risk (and it's many versions)
• Wintermaul and Wintermaul wars (along with all the other tower defense and tower defense wars)
• Vamperism
• Pest Control
• Many others as this list would drag on

I remember chatting with a lot of interesting people, though I didn't have any friendships I made move past Warcraft 3 in to other games.

I know there are many other games with custom games or customer game modes that the community developed, with DotA 2 coming full circle from being the sequel to a custom game to having custom games of its own.

To get the conversation going:

• What games had your favorite custom games?
• What custom games were your favorite?
• Did you make or contribute to any custom games?
• Any favorite memories?