"I have very good memories of Descent 3 online"
Most people who moved from Descent 2 to the third knew the third wasn't as good as the prior two. Also D3 was not as financially successful as the prior two games which lead to them cancelling Descent 4. Which means there were major problems throughout the game.
The biggest problem was that when they made D3 they didn't carefully measure the mathematics of everything in Descent 2, i.e. how the ship moved, how the weapons behaved, ship model sizes vs weapon sizes vs level sizes.
Descent 3's biggest problem was they didn't understand all the small things that made Descent 2 (which is just a beefed up D1) so great. The level sizes in D3 and perversely, the free form architecture and 'outside' terrain created these massive open spaces that severely destroyed the pacing of the action. What made descent so great was constant barrage of action in enclosed spaces. In D3 they made lots of things just way too big and many of the ships and weapons felt 'off' vs the kind of huge open spaces and free architecture they had. I enjoyed D3 multi for what it was but the feel of many of the weapons and corny introduction of ships with varying characteristics perversely ruined the series for me.
What made Descent was the equality of the descent ship with the INEQUALITY (aka you have x and he has y) that arises in terms of weapons. This is what took me years to figure out and put into words, inequalities should be encouraged in the domain of powerups, not permanent ship statistics. This is why Descent 2 was so fun, aka if you had plasma and the other guy gausss. The other guy had homers and you had mercury, etc. And you ran around the maze hunting for powerups when you were out. This kept the pace of the action going. In Descent 3 they totally messed this up and you can feel it throughout the entire game. Too much space and not enough action leads to serious lulls in fun and it showed up in the descent communities reaction to the game and in the sales.
What they should have done is slowly build off Descent 2's legacy instead of retooling all the powerups and ship models, they should have stayed close to the D2. The real problem was Descent 2 was so well put together and the dev's didn't realize what made it what it was. Basically when you change the object properties of the levels/weapons/ships/etc without any understanding of knock on effects you create unintended consequences for the feel of the game and the pacing of the action which is what Descent 3 developers sorely didn't grasp. Most of the fun in descent 2 came from running around and escaping other peoples powerups in small tight spaces. If we went back and changed things like ship size and hitboxes of weapons in Descent 2 and experimented you'd understand immediatley that the values for these things change the entire feel of the game when you combine them all. It's all those little values that 'feel off' when you add them together that makes you realize they aren't fit together properly in Descent 3.
I wish they could have open sourced D3, it would have allowed the community to fix and modify what the developers didn't understand. That being said, check out Talon.
http://www.talongame.com/