What is a faceup card?
A faceup card (as opposed to a facedown card) is a card placed on the table with its identity visible to everyone.
Even though cards are rarely dealt faceup, players usually have to play their cards faceup when it is their turn. This way, every player knows what card has been played, and they can make a counter-play accordingly.
One way 4 Seasons of War is different than most card games is that players do not keep their hand hidden from one another, but instead place their cards faceup on the table in front of them. Therefore, every player knows what cards everyone has, which allows players to focus their attention on strategic plays as opposed to memorizing card locations (which would be a big asset if the cards were hidden, since cards are regenerated from hand-to-hand and therefore kept in play in a trackable manner). However, some people like the challenge of tracking who has what cards. Therefore, the Alternate version of 4 Seasons is included in the rules for those that enjoy the additional memory component.