I'm very limited right now. I just Minecraft, Resident Evil 5, Left 4 Dead 2, and Skyrim (all are on PC). I plan on doing videos of some of my Minecraft creations, do Minecraft tutorials, and do Let's Plays of all these games.
I also plan on doing videos on Minecraft custom servers like SkyDoesMinecraft, CaptainSparklez, Yogscast, etc. (I'm NOT trying to imitate them)
And also multiplayer videos of Left 4 Dead 2.
Any more ideas?
Try to expand to things that people don't normally play, but would still be enjoyable to watch. Perhaps games that need some attention, like Brutal Legends, or just record games which are tailored to your game play *COUGH* THE WALKING DEAD *COUGH* so people can just see your reactions compared to theirs. By the way, what is your channel? Taking a closer look at what you already have would give people a better insight of what you want to expand to, that and I'd like to check out your channel myself.
I would say do not start with skyrim or minecraft, as many people are already making them, and like many other people, your videos have a large chance of getting lost in the archives of youtube. Resident Evil 5 Isn't a very popular game that is watched. I would say your best bet is to play Left 4 Dead 2. Hope this helped you out.
Well for starters, you should get SkyDoesMinecraft, CaptainSparklez and the Yogscast entirely out of your mind. They are actors, not youtubers. They are paid to read scripts for a living.
Searching for games that you should play isn't really that great of an idea. Play games that you find FUN, not profitable. And people will watch that.