# validation for placing cards:
- is the game still running
- is it the players turn
- does the card exist
- does the player have that card in his deck
- does the player have this card in his hand
- is the type of card allowed in that type of field
- is the field already blocked by another card

# validation for attacking another player
- is the game still running
- is it the players turn
- does the card exist
- does the player have that card in his deck
- is that card played
- does the enemy have remaining monster cards on his side
    - if yes a direct attack would only be possible if a effect allows it
- can this card attack
    - is the card of correct type
    - is it blocked by effects (will be implemented after card effects are implemented)

# player death management (win condition)
- does a players hp go to 0?
    - make the other player the winner
    - if an effect affects the playing player card priority comes first

# handle a player leaving
- check if game still runs
    - make remaining player win if yes   

# turn management
- server keeps track of each turn
    - whos turn is it
    - what turn state is currently active
        - draw state
        - place state
    - is the player trying to do actions not allowed in the given state