Twix House Rules 1.4 - Figured I'd post our final rules for anyone else to use

Twix AA Rules - b1.4
Multi-Turn Battles (encourages a slower and wider front for large armies)
  Place a marker for the defender of the territory to identify that the territory is engaged
  Each battle only progresses one round per turn (attacking aircraft must retreat)
  Each round of battle occurs during the original attacker�s combat phase
  Ownership for NOs, IPC collection, and production does not occur in engaged territories
Defender Retreating (gives them an option � albeit a punishing one)
  Defenders can retreat after any round of combat into any adjacent friendly zone
  When defenders retreat, the attackers get one full round of attacks without retaliation
Capitals
  Engaged capitals do not stop overall IPC collection; Captured capitals do not transfer IPCs
  Capitals grant 20 IPCs when taken or re-taken
The person rolling chooses which units take hits (for realism and more interesting choices)
  Aircraft dodge everyone (except fighters, AAA, AA guns, and ships) at 4
  Non-aircraft dodge fighters at 3
  Armor dodge inf/m.inf at 3
  Land units cannot target artillery or AAA until there are no other ground units remaining
  Sea units cannot target aircraft carriers until there are no other surface ships remaining
  The roller can assign multiple hits to a single target (which may trigger multiple dodge rolls)
  Units can fire in any order, but hits must be assigned to targets as they are rolled
Naval spotting (navy is less vulnerable)
  Before general combat occurs in a sea zone, attackers must roll to spot the defenders in order for a battle to occur
  A roll of 2/3/4 or less spots a defending navy of 0-1/2-4/5+ surface ships
  Defending navies can choose to engage if they were not spotted
  If a defending navy is not spotted and declines to engage, amphibious assaults still occur
Air interceptions (mimics air superiority, let�s fighters shoot down bombers before they bomb)
  At the defenders choice, before any round of normal battle, all aircraft engage for 1 round
  Strategic bombers roll at 1 in the air interception round
Turn order change (allows 2 players to have more consistent action in Europe 1940)
   Germany goes after America (Russia -> US -> Germany -> UK -> Italy -> France)
Research (makes it simple and less swingy)
  Each power rolls 1 die each turn.  On a roll of 1 they pick a tech tree and roll to see which tech they get.  You cannot research if you do not own your capital or it is engaged.
Combined Arms (boost to mechanized Infantry)
  Mechanized infantry attack at 2 as well as allowing them to blitz with tanks
AAA (makes em useful)
  Fires before each round (hits removed immediately) at up to 5 planes each
Battleships (the big guns)
  Fire an extra shot before each round (only hits surface ships - hits removed immediately)
Cruisers (AA guns)
  Cruisers, in addition to their normal attack, have AA guns which fire at up to 2 planes each
Facilities (airport, seaport, minor factory, major factory) can be destroyed
  They can receive twice their max damage (12, 12, 12, and 40) and then are destroyed

Research Technologies
Country

• Radar: Your AAA, facility AA guns, and cruiser AA guns hit on 1 or 2 and enemy navies adjacent to land that you currently and originally controlled are always spotted.
• Capital and Coastal Walls: During the first round of enemy amphibious assaults or capital assaults: your infantry, mechanized infantry, and artillery defend at 3
• Railroads: Your Infantry, Artillery, and AAA have 2 movement during the non-combat phase
• Research Focus: You roll 2 dice at the beginning of each turn for research
• War Bonds: During your collect income phase roll 2 dice and collect the highest roll in IPCs
• Mandatory Conscription: You receive two free infantry in your capital at the end of every turn
  Land
• Special Forces: Your infantry and mechanized infantry attack at 2
• Trench Warfare: Your defending infantry dodge everyone at 2, fighters at 4
• AT Loadouts: Tanks cannot dodge your infantry and mechanized infantry
• Thick Armoring: Your armor dodge infantry and mechanized infantry at 5
• Heavy Tank Guns: Your armor attack before each round (hits removed immediately)
• Heavy Artillery: Each of your artillery gives support to 2 infantry and/or mechanized infantry.  They also attack before each round (hits removed immediately).
  Sea
• Marines: During the first round of amphibious assaults your infantry attack at 3
• Super Submarines: Your submarines attack at 3 and defend at 2
• Heavy Transports: Your transports can carry an extra unit of any type
• Sonar: Your destroyers and submarines fire an extra shot before each round (only hits submarines � hits removed immediately) and enemy navies are always spotted by your navies.
• Heavy Cruisers: Your cruisers can take 2 hits
• Dreadnought Battleships: The extra shot from your battleships can hit any target
  Air
• Airborne Forces: Your strategic bombers may act as airborne transports. They can carry 1 infantry and 1 of any land unit. They have 0 attack and defense. They must start in a territory containing an airport.  They can only drop into 1 territory. Bombers paradropping units must survive both the air interception and the first round of AAA fire or their cargo is lost.  During the first round of a battle, paradropped infantry attack at 3 and other paradropped units attack at 0.
• Jet Power: Your fighters and tactical bombers attack at 4
• Heavy Bombers: Your strategic Bombers roll 2 dice instead of 1 and select the best result
• Surgical Strikes: Your tactical bombers produce 2 hits if they roll a 1 during regular battles
• Long-Range Aircraft: Your fighters/tactical bombers and strategic bombers have 5/5 and 7 movement
• Dogfighting: Your fighters roll 2 dice during air interception rounds

Note: Multiple abilities that alter attack/defense/dodge do not stack (only the highest value is used)