Hey, I've made countless card games in my spare time, and some important factors are variety, balance and creativity. Try looking up the Fullmetal Alchemist TCG, which features turns shared by each player as opposed to separate turns (decided by your card's total wits). This allows for more in-depth strategies. Also, there are no LP/HP, you win by accumulating victories in various locations, which had unique effects. This makes for an ever-shifting battlefield, requiring the ability to adapt. Yugioh may seem great and complex, but it lacks balance and is just a carbon copy of Magic (I have played both for years). I'd love to help and provide feedback/ideas/etc, so feel free to email me (lynxkuroneko@gmail). Take care!