well, gave this game a solo play through tonight, will do my best to get my group together to test a bit more extensively. First off - I'm going to point this out before criticizing, because I want to emphasize this.
Thank you for taking a rather stagnant genre, and revitalizing it with new concepts. Even solo, I legitimately had some fun exploring this game and looking at the new additions you've added that encourage a lot more aggressive play and keep the game from turning into a defend-fest.
The camps, the neutral mobs, the altars, and the need to gain EXP for your hero make map control a vital and important element of any game, and the somewhat smaller map size(Compared to other empire/civ builder games, that is) allows you to actually use your own base rather than being forced to slowly build siege camps.
The different heros also have abilities that help a lot more than most Empire/Civ Builder games, and the income building llimit, while I don't feel properly addresses all the cash issues these games tend to have (See later in this post) is a good step forward in it's conservativeness. The maximum income building limit being low allows for a lot less unnecessary and quite honestly annoying base building that plagues many other games of this type, as well as encourages people to go for the camps you have set up which give bonus money further.
Firstly, to get them out of the way, the only 2 bugs I managed to note were that the yellow text above the demonic shrine's never seems to disappear after being used, so that could be annoying for online play, and the second was that, due to my unit's skill-bar being full already, I was incapable of using a "New demonic skill" that I had obtained at one of the shrines.
As far as gameplay/balance issues? There's a few. The main issue I'm seeing, which harshly impacts the game on several levels, is just the lack of content I noticed.
Picking demon race, I noticed immediately that my entire arsenal was a main building with a mildly useful rush defense ability, a farm-like portal structure for income, a barracks of sorts from which I could build troops, and a hero altar. The troops themselves, while having a few different roles, were 4 in total, all immediately available, and around the same level of money to buy. there was only one type of hero to use, and he was obtainable very early. This is detrimental for 2 reasons.
1. It ends up making the map have no climb to aspire to, and causes you to have to stick to very direct strategies, even with the inclusion of spies and settler-specific free units adding into your unit composition
and more importantly, 2.
It becomes very difficult just to have enough production centres up to spend the money you gain given the relative cheapness of the units, giving the game the opportunity to become footman wars level in terms of spammyness - which, given it's really one of the only tactics to use in this game, is a likely outcome of this game.
I'd ended up picking demons, so most of my forces were about average according to tooltips. If that's the case, then some races are even spammier, which is a bit hard just to think about. This wouldn't be as much of an issue if there were more higher-level units to counter such tactics, or things like siege engines or the like to help punish such, but as it sits now, if two players are roughly even in money and both have a good amount going, an endless battle with no hope for any outcome but a stalemate can certainly occur - though, as noted before, the heroes do definitely mitigate that factor, particularly due to their possessing a proper ultimate ability.
Overall, it's a good game, - scratch that, a fantastic game - but it does have some problems that need some ironing out before it can truly shine, and a good dose of content will allow it to get a great amount of popularity