Re: Micro 4/3 wide angle options
I think the Olympus 12mm is wide enough, it's just not what most people would call cheap enough, I've gotten some spacious shots with my 12mm F/2 even indoors in a small 1 bedroom cabin, it's just not cheap!
The going price is $550, there was a fire sale on the Olympus store recently with a coupon that saw the price down to $395, but this is not normal, it's not a cheap lens, and according to some it's not that sharp, perhaps it trails the 12-40 by a margin but its not like its not sharp its just not cheap!

The Olympus 9-18 is neither bright or sharp enough indoors and even at F/4 your edges will turn into a mushy mess, it's not fast enough indoors at least not without a camera flash. While I've done some tricks with my OM-D I wouldn't use this lens indoors with out a flash if you were paying me to, perhaps you can salvage something decent, but it's no really a great lens for this.
Your choices are buying the very expensive 12-40 to get something on the margins of being sharper than the above, but not at double the price magnitude, or instead buying the 12-2, the 7-14 at F/4 you're going to run into the same issues as the 9-18 at F/4.
It's simply not exactly bright enough for indoor shooting without a flash, I can lie to myself and say this is good enough, but it's really not... It looks more like a water color painting when you come to deal with the amount of noise these cameras produce.
At F/4.7 ISO3200 1/12 the 9-18 isn't good enough for this, and I wouldn't use this for a commercial shoot like I did the one above, maybe if I was using it for a low-res JPEG on a website I'd find the detail smearing acceptable, but it's really not.
When you run into an indoor scene with no natural lighting like this shot taken from a gaming room, you'll find the issue with the 9-18, and with my 12/2 I would have gotten away with a shot I would have found acceptable by comparison above.
All well and good if you can turn a light on but sometimes you can't.

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All views expressed above are my own and are not an expression of how others should think, or a matter of group think for others.