I'd recommend from your list the Immoral Studies series. They are good for a quicky. Takes like 5-15 minutes to pass, and are pretty immoral.
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Current game is something that should have been shareware, as it is a satirical game criticizing the money-hungry game-developer industry. At the start you can only go right, so you have to pay for a DLC which allows you to go left. Then you become able to buy the next DLC to jump, and thus advance yet again in the game...
It's kinda short, and retro-graphic, but has 2 endings at least. Oh, and of course zombie-DLC is included too.