I think the idea of a bonus to military for having bordering tiles is a great idea. That's definitely one of the most clever while balanced core concepts I've ever seen.

The problem with it though is that after a certain point, the expansion bonuses change a cool gameplay concept into nearly free wins if you have a half-decent ideology tree and stay on top of the two building replacements.

I also thought that the gapping promotion was one of the cooler things I've seen, but it seems to come too early and allow for too much mobility, especially since it can move a whole army into siege positions in a single turn. If it was given by the generator and moved a few less tiles, I think it would be nice though. That way, you don't have what are essentially pike-wielding paratroopers.

I’ve definitely felt how powerful Yukari can be. I haven’t been putting much time into Civ5 in a long time but I can change things up slightly.

For the tech timings, I’m fine with them. While you do get gapping them early, you can’t attack on the same turn as you gap, really limiting the damage output and allows the enemy to get the first hit off. The armories cost more in maint as well, so if you want all your units gapping early it’ll either cost more or be slow if you’re building with limited cities, at least, that’s the plan.

I can increase the maint of these even more, so that it really limits your production of gapping units. This way, you’ll have to pay lots of money to keep up production of all gappers, or have a few gappers in your army and the rest normal. I’d prefer not to do this because a) money isn’t really a good balancer, too much variation in games and b) it doesn’t really fit into the core concept of the civ as a mobile force by limiting its units in that way.

I also have been floating around an idea that the jump starts out at 3, then a promotion can bring it up to 5. This way you can jump, but in order for it to be really significant you’ll need to give up a promotion. This could also be done by having the gap portal grant that promotion so you’ll need two buildings to get the full 5 instead of a promotion slot. While dynamic, it uses up one more promotion and there’s a hard limit of promotions in Civ5 and I don’t want to add in too many. I can also just set it to 4, like it was originally during my v3 beta tests. This number was later bumped up to 5 for some reason. It’s been a year so I don’t remember why.

Now on the topic of expansion, I don’t want to put a cap on the border expansion. The entire point of Yukari is to be as aggressive as possible while not killing anyone. With a cap there will be no incentive to expand into other civs after a certain point, or you can start redistributing borders to consolidate and remove unwanted civs, something I don’t want. It’s no different with gradient descent or negative values after a point. You just min / max off a certain number of borders and the expansion strategy isn’t a focus anymore. The problem is that this bonus is unnoticeable at first, but then scales linearly and becomes too noticeable. I have some ideas on how to change this one but they're complicated and I don't know if they'll be balanced either.

That all makes sense I guess. As for increasing a set distance in a gap jump, is that even possible? I know there are some aspects of this game that are hell to change, and that seems like it'd be one.