I've done a bit of trolling myself about 7 or 8 years ago. Trolling used to be an art.
Deliberate misdirection; Leaving people in a heated argument among each other.
Ah those were the good old days...
easiest way to find ideas, 1 what Mr Plant said, play different games.
easiest then that while you play games, set a goal in your mind, or on paper, similar to "category of game i want to make", "my target towards my dream game" "must have zombies, turrets, naked aliens, upgrades, lots of upgrades ,etc" you got the idea.
without a target set you wont get anywhere.
youl probably get ideas ... but they'll end up dumped cause you will want to try all of them. stick with 1 then when your finished with that move to next 1. and then youl be finding a way to get the best ideas out of each context in every days actions. like poor water from a glass can be a 5 minutes game. breathing air. avoid eating flying while you bike riding etc etc.
also i like to place my games in a targeted order:
Find 1 idea online or brainstorming and mold it to your needs, even improve one already existing game.
Sketch of game idea on paper or text editor.
Elements/graphic assets/sounds(creation or placeholders till u get something original)
GUI/HUD(user interface and game overall look)
Gameplay(here we fill in the game idea)
Optional Features(upgrades/purchases etc)
Optimization - make game run faster/gameplay be more natural/
Polishing - polish mistakes in coding,assets etc.
Release - YAY!
OR scrap all i said and just go here 49 ideas for games.