Large file sizes, how can i reduce them?

I have a small game ready for android however its a nightmare getting it to the play store.
The main issue being the HUGE file size of the .obb expansion files. I have got any of the starter material in my project and in fact my entire content is just over 10 mb, so why is is my .obb coming out at well over 100mb?
As you can see this is a huge problem for us looking to move to ue4 as nobody browsing the play store would download over 100mb for a small game that’s much like tappy chicken.
Im completely stuck here as ive no way to reduce my assets or sizes, and i cant release game so large in size. the thing that bugs me is the same sized project packages way less than 10mb on other engines such as Unity. Is this extra size due to blueprints?

p.s if its any help im getting this pop up with google play when uploading my apk and .obb http://i.imgur.com/KJKu3wD.png
What is making my build so big and how can i reduce it?

Ive just packaged a new project with no starter content, deleted the basic assets such as lights from the scene, and this still comes up 20 mb for the apk, and another 26-27mb for the obb! its way to big

After looking some more. It seems I’m cooking a lot of u needed engine content? Is there a way I can just cook what I want?

Did you find any solutions? I’m facing the same issue.

What deployment mode do you use? (Debug, Development, Shipping)
I’m not sure about the sizes after deploying, but using Shipping might decrease the size. Unreal isn’t as polished for mobile though (yet), so the files will be larger than with Unity f.e. (at the moment).

When you package your project, I recommend focusing on either ETC1 or ETC2 texture compression. ETC1 does not support alpha channel, which means textures with alpha channels will be uncompressed. If you do a full package with all texture compressions, it means that you multiply the file size by the number of texture compression types. Try only ETC2 to see how small the package should be with only one texture compression available. ETC1 is supported on the majority of Android devices, so if you need it you have to make sure you work around the alpha channel problem.

Settling on one compression type should greatly reduce your file size.

We need a detailed guide of how to reduce final product file size. How to omit engine modules that we are not using.