Dynamic events in both Rift and GW2 scale according to the number of players in the area. The algorithms used are opaque to players, but the number of creatures and the tempo of attacks will increase if more players are present.
In Rift you have the rifts themselves as mini-events to clear, good small-group content but possible to solo if they’re of the minor variety. Invasions on the other hand are pretty impossible to solo, they usually have time limits and they seem to usually have an ‘enrage timer’ (to quote standard MMO boss mechanic lingo); that is regardless of area population the number of invasions attacking the bases will increase over time.
My Rift play session today was dominated by two unplanned attempts at invasions, both ones I’d not seen before and both of which ended in failure. In the first case while questing in Ember Isle an event started with activity right next to me. After some failed attempts at attacking the nearby life idol, some other players appeared and we started working to clear the event, in the end it failed suddenly without warning – I guess we were playing too offensively and one defensive base too many was defeated.
In the second case in Iron Pine Peaks a long hard battle with a smallish party was finally defeated at the final boss stage by the loss of the last bulwark. This time after completing most of the invasion with only 4 players we were suddenly up to 8 or more. I suspect this had something to do with the sudden failure. The system will scale up to keep the challenge relative, but if all those new players aren’t up to speed or aren’t actively involved straight away then the poor remainder (including me) are left quickly overwhelmed by sudden waves of invasions reinforcements.
I haven’t seen anywhere near this level of scaling in Guild Wars 2′s event system, although the sheer scale of events is generally smaller (I’ve yet to experience a dragon fight I’ll admit). This presumably makes it easier for ArenaNet to balance events around the number of players at the lower end; though the inverse of that is just how easy most events are in GW2 if there are lots of players around.
There’s a difference whether intended or not in how the two games’ event systems scale. In Rift the game will push challenge up quickly as number scale and can keep doing so into a full raid or multiple raids. But at the lower end the game is pretty harsh to undermanned parties – invasions are not meant for a lone group. In GW2 the event system scales pretty evenly, much better at the lower end though there’s a lower threshold of participants at which it gives up to the ‘zerg’.
I’ll be interested to see if the influx of returning and new players with Storm Legion’s launch will make invasions more accessible once again.