GMod is the OG mod that showed us all just how much potential lies within the Source Engine, and within games in general. It's the mod with 1,000+ game-types. I don't think it's retained quite the same magic that It'd had back in the day, but the community is still thriving, and you can still pretty easily lose yourself on one of the servers for hours at a time. For $10, few things compare. Garry's Mod is a classic.

Disregarding the monetization, Apex is a great shooter with buttery smooth movement and an engaging roster of legends that can work together in some pretty dynamic and interesting ways. The maps provide good options for mobility that reduce downtime and the option to play either BR or arenas means that most will be able to find a game type that they enjoy. Though there haven't been any in a while, limited time modes periodically also provide a fun and fresh take to the formula. Play solo or link up with some friends that you vibe with and you're pretty sure to have a good time.