We use D&D 5e as base for the rules of this game. Changing a single thing in a ruleset can break it. Implementing shove as bonus action did exactly that.
As per PHB of D&D5e :
"Using the Attack action to shove a creature, either to knock it prone or push (not throw) it away from you. If you're able to to make multiple attacks with the Attack action, this replaces one of them.
The target of your shove must be no more than one size larger than you, and it must be within your reach. You make a Strenght (Athletics) check contestet by the target's Strenght (Athletics) or Dexterity
(Acrobatics) check (the target chooses the ability to use). If you win the contest, you either knock the target prone or push it 5 feet away from you."
This is the exact wording. No Bonus action, no throwing over walls or to the moon. 5 feet are approx 1,5m.
We also miss the "ready" ready action, which has a big impact on combat.
Dash, Disengage, Dodge, Help, Hide and Grapple (wich we don't have) are also actions.
The bonus action as per PHB:
"Various features, spells, and other alilities let you take an additional action on your turn called a bonus action. The Cunning Action feature, for example, allows a rogue to take a bonus action. You can take a bonus action only when a
special ability, spell or other feature of the games states that you can do someting as a bonus action. You otherwise don't have bonus actions to take.
You can only take one bonus action on your turn, so you must choose which bonus action to use when you have more than one available.
You choose to take when to take a bonus action during your turn, unless the bonus action's timing is specified, and anything that deprives you of your ability to take actions also prevents you from taking a bonus action."
That makes it pretty clear why Larians decision to change the bonus action almost totally changes the dynamics of 5e combat. 'nuff said.
