Mark as I understand it you can, but you have to purchase an export license for each iClone prop or figure that you take into your game. When you are in the Reallusion Content Store, you'll see two prices usually, one that's for use in iClone only, and the Export Price. In addition to that, I believe that you will need the 3DXchange Pipeline Version in order to do that
You can find more information at the link here
.When it comes to animating:
Yes, you can create your own poses and animations in iClone. The animations that you create yourself, you may export, but if you use purchased animations, then you need the export license in order to use them.
Yes, you can animate more than one figure at a time in the scene, however --you have to export each figure's motions independent of each other. When it comes to using iClone content in games, there's no easy answer to this question.
If you're looking for a blanket yes or no, then you're going to be disappointed. Each figure and prop and how it renders elsewhere depends on how much work you are intending to put into the game. There is no "easy" button when it comes to developing game assets. A lot of this is going to depend on the game engine you're using and what you're trying to do in the game and that's not just the figures. Your lighting, rendering engine and style of game is going to all come into play. If you are going down this road, it's probably best to start with the development platform that you are going to use, and see what's possible and not possible in that environment. My advice to you is to stop where you are right now and before you go buying this or that, do the groundwork that comes first. It's just my opinion, but I feel if you're going to do a game, you should model for your game engine and not for your animation tool. It's not possible to export Content Creator Characters without a license, so you can't use a trial version, so you have to decide for yourself whether or not you're willing to risk spending money in iClone content only to find for whatever reason they don't work well in your game engine. If you do some tests with various geometry styles and poly counts, you'll get an idea for what is going to work and what won't. Then you can show the examples to the users here and I'm sure someone will be more than happy to put some tests up for you and see if they can match the results.
I'm saying this because I noted in your post that you said you wanted to make a game, but you mentioned none of the things that would need to be known in order to give you an accurate answer. What game engine are you going to be using holds direct bearing on the answers to your questions about models and how they perform. The best we can do at this point is give you some general areas to concern yourself with but the simple truth is you won't know until you try. If it works, then fine but more than likely you will have to do a lot of tweaking in order to get those assets looking the way that you want them and performing at their best. iClone is a pretty easy system to learn, but it's not a one click solution to what you're after. Game Development means that you can't rely on others to make sure that your game characters look right or perform well in your game. From what I read of your post, it looks like you're looking for things you can just hit the ground running with, and that's probably not going to turn out well.
I would start with your game engine and work back from there. Find the assets that you want to use in your game from the game engine resources. Unreal Engine 4, Unity, Cryengine, Stingray all have their own shader systems for assets. You're going to have to work with getting your assets looking right in whatever engine you choose, then bringing them into iClone to animate. That includes the characters themselves. I believe you're looking at things from the wrong perspective in that you want to get your characters game engine ready, and then bring them into iClone to do your animations. That way, you won't have to worry about things being compatible because you will already know they are all right in your game engine.
I say this from a tiny bit of experience --it's better to start and do everything as far as geometry, textures and shaders and make them for the app you intend to do the final work on, then take them into whatever package you intend to do the animations in --this way they don't have to really look right in iClone if you're not going to be doing the final animated outputs in iClone. Realistically, you could even just put together dummy figures with identical bone structures, work out your animations and then export your animations in FBX to your game engine if they're just simple characters. Now if you're going to want to do things like export the cloth animations in alembic --that is a whole 'nother story. All of this is stuff you have to decide before you start going to look for an animation package to do the work in.