
Originally Posted by
Ibi
Under vertical progression, the developer knows that the items a player is getting within any tier will be made obsolete in six months. As a result, they can set a drop rate such that a player will, on average, get all (or almost all) the gear they need within that six month period, because there will be something new coming in by the time they're done.
Under horizontal progression, the developer knows that the items a player is getting from any particular event could remain relevant for several years. If they set the drop rates the same as they were in the vertical example above, then their player base is done with that particular event in that same six month time frame. So far that's not, in and of itself, a problem.
In both cases, the developer is adding new content at around the six month mark. But where the vertical progression developer doesn't need to pay attention to the old rewards when creating their new event, the horizontal progression developer needs a way to add drops that serve some sort of purpose, while not making the old items obsolete.
If you make the items effectively equivalent, the players are effectively done with the reward from the new event before it even starts. If that's the case, the event needs to be entertaining enough to be worth doing despite the rewards, at which point the event would have worked equally well under a vertical progression system.
If you make the items better than the existing items in some situations, and worse in others, now the player needs to collect an entire second set of items and also hang on to all the old ones. In addition to now needing to carry around twice as much gear, the player isn't really getting any more powerful, they're just switching out one thing for another depending on the situation (and likely still not really having a choice in the matter).
The alternative to this is to make it take much longer to get all the items from any particular event, and then add parallel alternatives through which to (hopefully) obtain other items to fill in the gaps. Each event ends up with a much longer life span, but only because you need to run it more to get the same results.