Alrighty, so a few of you may remember the Rescue Camp's Retrodes that actually crawled up from the floor like zombies.
Good stuff. That right there would be a fine addition to the way Retrodes function normally.

Also, implementation of OCH's Gremlin Bunkers into the arcade, being reprogrammed to spawn enemies such as Mecha Knights, etc.
at a rate of one every 30 seconds, creation of one 5 seconds after a spawned one is killed, and requiring that a few switches be flipped before the bunker can be taken out. Gives a challenge.

Lastly, fairly-common scenario rooms with things like Battlepods or other mini-bosses that have unique attacks.

Thoughts?