I tried playing, but I couldn't connect to the master server.
I toyed around with the classes and they seemed neat, but I couldn't see the whole game screen for some reason; that kind of limited my understanding of the game.
Overall, it seemed neat though.
Um...?
What do you mean you couldn't connect to master server?
I mean there is no master server to get the list of servers lol.
Gloom is a quake 2 mod back then we had address book for servers and we had to relay on IRC or webpages for servers

Kinda like web pages in late 80s when there was no google.
To get servers visit:
http://q2servers.com/?mod=gloom&g=*&m=*&c=*&ac=*&s=&player=
The only servers that have players are munimtalo and quake.de.
Quake.de have like 10 players per day from 19:00 pm till 0:00 except for suterdays and sundays then it has around 20 playes.
And yeah the classes are awesome if you play human the best are commando, mech and for aliens stinger, stalker.
Now I know alot of people who play gloom will say guardian is better then stinger but stinger has immunity toward lasers so human exterminator (battlesuit + jetpack + pulse rifle in trem lol) is useless against it not to mention human laser based defenses.
ANd also not to mention stinger great HP, Armor and most of all his flamer that cooks almost every human weak class.
Oh almost forgot for people that are interested check gloom guide to get easy started:
http://www.planetgloom.com/gloom_gameplay_information.html