Thunderbrd
C2C War Dog
That change was because double terrain movement was causing all early ships to be able to move into and then out of reef and coral plots without being stuck on them when only kayaks and outriggers (early exploration boats) were intended to be able to do so.
Coastal plots cost 2 movement as a base terrain with wooden ships having double movement in coast terrain. This is meant to make each coastal plot only have a cost of 1 for wooden ships, which is not supposed to completely negate the cost of any features in those coasts.
What that first change attempted to correct was the fact that the plot would, in this order:
1) Tally up the movement cost of terrain + feature.
2) Limit the cost of the plot to the movement remaining on the unit. (this is the step removed in that revision)
3) Then half the movement cost for each applicable double terrain or double feature (I'll include hills in this as a feature for the remainder of this discussion though it's somewhat a special case). Thus if the unit had forest double move, the plot overall cost would be halved if it had a forest, and if it had plains double move and the forest was on a plains in that plot, the unit would halve the cost of the plot again. (There's kinda an undiscussed bug in this too if you think enough on it.)
By limiting the cost first, no amount of movement cost placed on a feature could stop a unit with 2+ movement that had EITHER double terrain OR double feature movement applying in that plot.
So my original analysis saw it as a flaw that we were reducing the total before we halved (then potentially halved again) the cost of the plot to the remaining movement of the unit.
Taking that away and giving explorers double movement through reefs and coral ALSO did solve the math equation for that, but then a one space movement wouldn't get the added movement if they moved into a forest if they had double forest movement. That was the bug reported, which is what you are advocating the rules system should work like.
If that were to be the rule, then the promotions to take double forest movement and double hill movement would lose all value in 90% of their applications and they are situated on the promotion tree in a location that makes a player have to go a little suboptimal to get this ability, which can greatly enhance the speed at which you get some exploration and hunting units to get around the map, particularly the tougher ones, also a key component in a strategy for making axes and spears capable of often getting quickly into a surrounding position for S&D. There's a number of play strategies that hinge on this working as it was originally designed. Which answers your question of why it's important to retain this expected behavior and to not let it be obsoleted by other rule changes.
So as I looked at this again, I realized that in the situation we have now of an additive move cost between terrain and feature, there are now two halves of a cost equation to consider, not just one. Furthermore, that feature double movement is simply meant to be more powerful than terrain double movement. You want a mounted unit with double movement through flat terrains to be able to half the movement cost of the flat, unfeatured terrains he moves through, but not completely be able to move an extra space through a flat terrain with a forest, but you DO want that one space moving axeman to be able to get through that forest plot and move to the next before his movement is up. Thus the terrain double move doesn't even apply IF there's a feature there to replace the most important aspect of that plot AND you have the feature move doubling ability that applies to that feature. However, you do halve the movement cost of the plot if you have a feature there and it's the right terrain you have the double movement for, but that may well not mean that you're going to get through it in full because the terrain and feature on it do add their values together. But if you HAVE the feature double movement, you must be assumed to be able to get through the terrain under that feature with the same amount of efficacy.
I know it's complicated but it's important that it works this way for the sake of a lot of tactical strategy that the game has been founded on from the beginning to be applicable and for other complaints (Such as DH's complaint that he couldn't set the reefs and coral to any amount which would be enough to stop wooden ships with more than 1 movement) to be addressed properly as well. Now both situations work. Maybe this could bring up some other situations but ultimately, the math actually does make sense to the intention of the tags and it's not really the hack it looks like so I'm fairly confident this is the proper movement equation.
The main thing to understand is that feature double movement insists that the terrain underneath that feature is also considered halved if the feature exists there but terrain double movement does not have a second half of the total movement cost equation to be concerned about and does not demand that if there is a feature on the plot that both halves of the equation are halved, only that the sum total of the plot is, so that features may still be able to stop the movement of units with double terrain movement, even on a plot that has the stated terrain.
