System Changes:
Frontlines on allied territory against non-allied neighbors are now available for player/AI assignment. Allied nations will send units to help an allied nation (player or not) during wars.
Adjacency check added to ensure nations do not steal occupation of tiles if they do not occupy a tile adjacent to the captured tile. Allies will claim occupation of tiles their units capture if they have at least one tile adjacent to it. Player units will follow the same logic to minimize exclaves.
Combat simplified. Border clashes (when two units attack one another at the same time) have been removed since it's unnecessary. Combat is now attackers vs. defenders.
Units now evenly distribute across frontlines. Previously, only one unit was sent to cover empty tiles and large stacks did not distribute themselves post-arrival to the front.
Encircled AI divisions now more aggressively seek to free themselves.
Frontline assignments now overwrite already-assigned units if they are selected and assigned to a new front.
Attacking units can retreat at all times (no longer pinned at late stage of combat).
Battles now last longer.
Balance Changes:
Austria's initial army was increased from 40,000 to 200,000. Hungary's initial army was increased from 30,000 to 150,000. (40,000 and 30,000 was apparently the size of their national forces at the time, Landwehr and Honvéd, not including their common army, so these numbers should be more realistic now).
Bug Fixes:
Battle indicators were not showing up, but now they are fixed.
Units were going back and forth while fighting in battles (interpolation bug); now fixed.