There's a catch. There's always a catch.
Released in 2009 and getting a second part two years later, Escape from City 17 was an excellent Half-Life 2 fan film notable for its nearly blockbuster-level CG effects. Ironically, it is the CG effects themselves that are keeping Part 3 from being released. But have no fear—there's an IndieGoGo campaign to fix just that.