More of a house rule to a card game, but War with 'Hero Hand' house rule included.
•Conscription Deck: Regular cards, standard War rules. No peeking. Memorize, okay. Card counting, okay. They're your deck.
•Hero Hand: Start the game with each player dealing 5 cards from their conscription deck into their hand. These are known heroes of the force. Basically, they're random cards, but you know them now (it's as random as XCOM soldiers. Some are awesome, some are crap; others, lethal joke characters (if you permit "2's Beat Aces" rule, or 3's winning a round against a 2; especially if your opponent was expecting you to play an ace)), and can play any of them if you so choose. To reclaim a hero, survive 15 more rounds (conscriptions only) without playing another hero to add to the hero hand. Maximum cards allowed in Hero Hand: 5.
Now the game has a strategy element to it.
EDIT:
A modifier to the game: Start the game with no heroes, and build up from an empty hand (0 to start, and accumulate your 5 heroes (65 rounds of conscriptions straight; 75 if 7-Card Stud)).
EDIT EDIT:
Yet another. Integrate other games as playstyles. So 7-card stud rules. up to 4 visible (face up) soldiers, and 3 hidden ones (stealth force, face down/hand) as your Hero Hand (cards provided in same order (constant loop: D-D-U-U-U-U-D (same limits too)), and you can also play the conscription deck (again, 15 cards to replenish heroes). 7-Card Stud must be supplied by your own deck, so if you run out of cards, you're out of luck. I wonder how Texas Hold'em hands would work? Community hand as Mercenaries or Soldiers of Fortune, and 2 heroes for your main hand (would break the game, if not for the 15-round replenishment rule; replenishment exchanges between players by alternating (2-player) or rotation (3+ players/dealer chip), by the player (individual values to conscriptions))?
Reminder: If you don't recall, you have the option of the rule of 'Keeping your kills and soldiers if you win the duel'. And the other rule of 'If both players play equal value, draw 3 cards (epic duel/brawl), or alternatively, draw 3 cards, and play one more. Winner collects all played cards'.
This game can get nasty if you involve more than 2 players and
card decks (generally the default is 2 players and 1 deck of cards; not 4 players and 8 decks). Jokers/Harlequins are optional.
WARNING: Those kinds of rules may need to be kept in a ziplock bag, lest it quickly becomes an amoeba that'll absorb more of your playing cards until it becomes a sentient playing card golem.
EDIT EDIT EDIT:
I'd like to see how Solitaire vs. Solitaire would play out. And yes, Game vs. Game matches of War (different nations, different rules/playstyles). So, imagine 5-Card Draw (with it's own delays involving 15-card replenishments) versus 7-Card Stud vs Solitaire? Who will win? If more than 3 players, how much ‼fun‼ is to be expected? If Egyptian Ratscrew rules are also applied, how much vulgarity can come out of a single person?
•Solitaire: You play Solitare to voluntarily reveal your (hidden) forces so you can know more about who you're sending, and who you'll be gaining (or sending out instead upon reveal). However, your leaders can get a little nervous, so they send the shrimpiest troops before themselves (assholes. basically, revealing more cards is played out exactly the same way as the game plays (54321 RBRBR)). You can also deal a new set of 3 troops (and progressively play them (top-most card first, and downward from there), or use them to reveal more of your forces to change your strategy) every 15 conscriptions. Revealed cards are not lost in play, but hidden again at the end of dealing pass. No shuffling after making a round with the conscription deck. You can play Solitaire at any pace you pick, but conscription is required to deal another reveal of playable-3(-2-1). With "Play From 0-Cards" rule applied, this game will suck.
EDIT EDIT EDIT EDIT:
Considering accumulating forces comes to play, this actually still makes some sense. With amoeba decks (4+ decks mixed together), Solitaire will never play the same way even moreso, since you could have bad enough luck to get hit with 16 3s or 4s at the same time (even worse if they're all exactly the same kinds of cards).
EDIT EDIT EDIT EDIT EDIT:
•Tri-Peaks: Same basic setup and rules as play. You can exchange a card played on the field with one of your visible cards (and 1 revealed random from conscription). You can also trim your forces by playing your game of Tri-Peaks, like with Solitaire, a bit to improve your strategy/game by going 1 value above or below revealed random (only that pile is permitted to accumulate from the Tri-Peak game).
Had to simplify it a bit. I started over-complicating it again.