General:
* Implement
* Execute
* Carry out
* Put into effect
* Pass (for laws)
* Establish
* Introduce
* Authorize
* Approve
* Sanction
* Enforce
* Perform
* Stage (for plays)
More formal:
* Legislate
* Ordain
* Decree
* Promulgate
Informal:
* Do
* Bring about
* Make happen
Specific to plays:
* Stage
* Perform
* Present
* Produce
* Act out
The best synonym for "enact" will depend on the specific situation and the desired tone.