Imagine that someone came to you looking for some money to build a giant stone tower, only they propose to build a tower that leans rather than extending straight upright. Though this project might turn out well, the possibility that it might tip over is an obvious concern with the design, and you would want to see how the designer proposes to address this.
As I've learned a bit more about the upcoming Rifts: Planes of Telara game, primarily through The Rift Podcast, I'm seeing a pair of leaning towers occupying some prime real estate in the game's design.
Class Choice Versus Balance
Rift is offering a flexible class system - characters are locked into one of four callings (archetypes), but they customize their actual role within that archetype by picking three of eight available souls and dividing advancement points amongst the three as desired. This sounds like a lot of fun on paper, and players who have tested the system at preview events have come away impressed.
The potential concern is that someone needs to decide how difficult to make the actual game. Do they balance things assuming the best possible DPS, healing, and tanking, leaving everyone who doesn't look up and adopt a cookie cutter build out in the cold? When players show up with a full group of completely unpredictable characters, does a tough encounter suddenly become trivial because some obscure combination of abilities leaves the boss helpless?
Though the issue is not necessarily insurmountable, most other MMO's struggle to balance as many as a dozen classes. Unless the point is that players are supposed to swap into a different optimized role for every fight, it's going to be interesting to see how Trion handles this.
Dynamic Content Overload
The game's other heavily touted system is its dynamic content. The namesake rifts open up around the world, allowing NPC's from the elemental planes to attack Telara. If players fail to close the rifts in time, NPC invasion forces will spawn and march on towns (or even each other). Again, players' first impressions of the system in limited preview events have been very positive due to the sheer novelty of the mechanic.
The concern here is what happens a month or two into the game's release, as everyone has shown up at least once to find their questgivers dead and had to repel an invasion to get their towns back. (In some ways, it almost reminds me of Warhammer, with the non-instanced RVR replaced with NPC's who will conveniently show up in beatable numbers and can be counted on not to abandon their conquests because it is more profitable to allow the other side to retake each keep so that you can re-re-capture it.)
Will midlevel players log in a few months down the line to find their towns demolished by armies of elementals, after the majority of the population has moved past that level range to the cap, with limited interest (or patience) in returning to bail out their new comrades? As we saw with WoW's notorious zombie invasion, players will eventually give up on saving towns from attacks that will continue indefinitely no matter what players do.
Toppling in 30 days?
These issues can be addressed given enough time. The thing that concerns me is that both of these topics are things that will not be apparent in the first hour or day or even week of the game's release. Endgame class imbalances and invasion fatigue will kick in only after players have had the chance to actually get that far into the game, which won't happen at a press event or a low level beta weekend session. (For the same reason, it won't show up in press reviews, or even the opinions of real players during the first week of launch.)
The true test comes at the 30 day mark when subscription fees come due. If players are blindsided by these issues (or others) and leave en masse, the sharp negative turn in word of mouth can be more damaging than the actual in-game issues (which, in my view, we saw with Warhammer). The longer the game goes without permitting sustained high level testing in an open, non-NDA environment, the greater the chances that the leaning towers will topple before they can be reinforced.