This is a very early review, so take it with a grain of salt.
I'm still on my first game and I can see why this game is so popular. 4x games are notoriously complex, with a large variety of systems at play. While not cutting too many corners, AoW4 manages to distill the greater part of the information it throws at you to just about the simplest form possible (kudos to the UI team I guess). It's a full 4x, but it feels more like playing an rts in terms of complexity. I spend less time poring over stats and more time focusing on my armies (which could be a pro or con depending on you playstyle). While maybe too simple for some, the ease of access is welcome (I am no longer a young gamer), and helps to foster the 'one more turn' appeal of the genre.
Customization is cool, but I haven't played long enough to really see how it affects your faction mechanically. Aesthetically it's a blast though, despite a glaring lack of ponytail hairstyles.
Combat is... good. I'm not good at it yet, but it is enjoyable.
Overall I'm not completely floored by AoW4 like I was with Endless Legend (an absolute must play of the genre in it's day), but the wide variety of aesthetic options, easy to digest information, and strong combat will keep me coming back for a long time. If the devs ever add a trading marketplace like the one in EL, this is subject to change, lol.
Game seems to run okay on a 1660ti, although the initial load takes a very long time (granted it's pretty much the only load in a session).
tldr: good game if you want a 4x that plays like an rts
Kudos devs!
