Some general guidelines (remember, this are being re-evaluated as the game unfolds:
* if you\'re more than 4 away, play defensively
* if calling a tile would make you further away than you are right now, do not call it (this includes calling kon) (ties would be for a non-low level ai)
* if your hand is eligible for riichi, three things to consider 1) how far from the end of the wall, 2) likeliness of the current waits 3) how likely is it to add a yaku, or better waits (this may be somewhat simplified for the low level ai)
As for discarding, the AI would assign two weights (numbers) two each tile in hand: on offensive discard weight, and a defensive discard weight. Then double the importance of the weight of the way the AI has chosen to play (offensive or defensive).
As for being offensive or defensive, like I said above, if the hand needs more than 4 tiles to be in tempai, play defensive. If another player has declared riichi, and you\'re \"not close\", play defensive. If, after 10 turns, you are \"not close\", play defensive. Otherwise, play offensive.