@JuanMaddox 1914 is very different fundamentally from the other A&A games in that the combat system is completely different from what you’d expect.
Naval combat is the same as usual, but there’s no Destroyers. Just Subs, Cruisers and Battleships. Repair rules for BBs are the same as G40.
Land Combat and amphibious assaults are much different, though. Aside from some combat value differences, here’s the main changes:
Land Combat only takes place for one round. If the attackers and defenders fire and units are still alive on both sides, the territory becomes “Contested” (i.e. no power collects IPCs from it).
Before rolling for Land Combat, all FTRs in the territory have a battle independent of the land units. This battles continues until one side is wiped out. Whichever side still has FTRs remaining at the end of this Air Battle gains something called “Air Superiority” for the following Land Combat, which results in that side’s Artillery rolling for more than usual.
If you conduct an amphibious assault, after shore bombardment (which works like in the other games), the defender gets to bombard your land units with any Artillery units on the territory being attacked. Any units killed by the Artillery counter-bombardment are removed and do not get to participate in the battle.
ART cannot move without an accompanying INF. Additionally, you must leave at least one INF in any territory that is Contested at all times. You cannot take ART/FTR/TANK units as casualties in battle before you lose your last INF.
As far as house rules go, I recommend playing under the LHTR for this game. It makes a few core changes to the gameplay that speeds things up (land units can move 2 under most circumstances, countries can be made to “surrender” and remove all of their units from the board, etc.). It also balances the game a bit, as OOB highly favors the Entente Powers (UK/France/Russia/Italy/USA).