So, you can't write English well, nor hire someone who can, you have CG skills that make this look like bad doll dress-up (Sindy in a dress done in camo, which is nothing like any military outfit ever, anywhere, outside of some kid's imagination), and you can't think up a non-copyright way to use a giant robot-like vehicle without calling it a BattleMech (TM) ... of course you decide to apply these 'skills' to create a VN/Game.
Uh-huh...
Okay, now the advice. In this genre, writing matters. You are telling a story, and spelling and grammar are the basic and essential tools and materials. If good writing isn't your strongest suit, then you will need AMAZING quality CG to make up for it, and try to tell the story mostly in images with few words, or else you absolutely need a better writer and editor to bring the writing up to something that people will feel they'd be willing to pay for.
Writing about things you know always is easier. Anywhere you have to use any degree of imagination is where that story may have holes people will laugh at because they know more about the topic otherwise. If you want to tell an extreme story then you honestly need to do extreme research, just like every other writer who does it right. You'd need to learn more about military and paramilitary organisations and structure, for instance, along with doing all the research you can on robotics and engineering. Anything you can't research well, find ways to avoid. If that sounds like a lot of work, it is ... but it is because it is work that those who do it can hope to eventually get paid for it.
Be careful about using the intellectual property and trademarks of big brands. The laws of intellectual property mean that the owners of a trademark have to sue anyone breaching it, no matter how small a breach, or even if there's nothing financially they could get from a suit. Because if anyone can prove that a company hasn't enforced its trademark in one prior case, has grounds to claim that they believed the trademark abandoned. Meaning, if the owners of the 'BattleTech' and 'BattleMech' trademarks doesn't sue you, then they won't be able to sue the next movie, game, or toy maker either, nor any others. And all the millions of dollars they make in franchising and licensing are lost.
Or you can just hope that they never find out, even though they have millions of dollars on the line for NOT finding out, and so pay people to constantly look for breaches...