The other suggestion would be to turn the speed for all movement directions to be the same.
Speed is same, but it just appears to be different, because this is how space is represented in this kind of view: https://en.wikipedia.org/wiki/Isometric_projection
As you can see it seems wider than higher, but it is same. So, something needs to look traveling faster left-right than up-down.
And just to add on flare, often mentioned, flare and EK are totally different projects, different engines, but many people confuse how something looks like and how something works, thinking it is the same. Assets that flare and EK use are free assets and everyone can use them.
Also, David shared some of assets made for EK with flare project, as well as he contributed to flare project in different ways.
So, there's some visual similarity (on old levels, new ones are different as they use assets created for EK exclusively (but as mentioned, some are shared with flare, so they can be seen there also, but they were made for EK)), but these are two completely different games.
More info on assets and flare can be seen in credits: http://exiledkingdoms.com/ek_credits.html