Lone_Scout: Sorry for not noticing your post, EtG is one of my favourite games, so I'd suggest that, at this point, you stop reading this post, go buy the game, and start playing it till the end of days.
And yes, EtG is regularly updated on GOG, so it's a worthwhile buy.
Risk of Rain is also a good choice. Requires more skill, though, but definitely worth playing as well.

Basically, what the Advanced Gungeons and Dragons Update introduced:
- More guns and items
- New enemies, and an improvement on some of the existing ones.
- Item combinations. Getting two items that combine with each other now leads to some badass upgrades. This combos include: Dual wielding, extra ammo, extra properties, different shots, visuals, speed upgrades and a huge etc. It brings a handful of nice surprises. This part contributed a lot to rebalance the game, as some average items can turn really good with a combination and the game is no longer so dependant on getting some lucky powerful item drop to have a better chance.
- A new secret chamber with a really though enemy boss (for experienced players). Take your revenge on the Resourceful Rat. If you can...