The coders do not ‘own’ any code, your company does, as long as you create a contract that mentions that. You will however have to trust people with your assets and code, as long as they are freelancers working on their own PCs. Legally, they are not allowed to use your IP’s assets and code, but again, I think all that must be clearly written down in the contract. If anyone steals from you, publishes your game, and makes enough profit to justify suing them, you can sue them.
Now… in the real world, imagine I’d work for Ubisoft and steal their next Assassin’s Creed game, and launch it early under a different title. The first thing that happens is that nobody knows about me and my game, and nobody will be playing it, unless I have enough marketing budget. It’s like posting Lion King on YouTube and naming it… ‘The Little Lion that Could’. Nobody will find it. Secondly, it would be obvious that I stole content that is not mine, and sooner or later, especially if my game reaches an actual audience and makes some money, I will be in legal trouble.
You simply need a contract, legal and clear, that explains who owns what, what your company’s rules and expectations are, so on… you know, legal stuff.
It’s a matter of trust as well. If I work for you, even on location, on your company’s PC, and you give me access to internet, it’s highly unlikely I won’t be able to save my work or in other words ‘steal’ from you. But it’s also unlikely I would or even could do anything damaging to your company by keeping any of your code or assets. At worst, I guess, I could steal your entire game and simply launch it myself, and maybe make some money if I’m skilled with marketing. If I do an asset flip and just keep your code, maybe it would be good for business for you too. People always look for the same stuff they played and liked, and want more of it. Or me stealing from you can start an internet scandal that ends up helping you get visibility, free marketing. If it’s not good for your business, then you can sue me, prove that I’m doing something illegal, and that I’m making your company lose money, and most likely you will win, because you have legal proof and I have nothing.
In any case, all this assumes that you know what you’re doing and that your game has a chance to be successful. Most games ever made, or even published, are obscure Indie titles and have close to zero players. So if you have little budget and no experience making games, you’re worrying for no reason. You should first try making a bunch of games, get to the point where you’re hopefully able to make a great game, start making that potentially great game, and then you can maybe have a reason to worry about it. ^ ^ But like with any IP, you can never know… until you know. You can keep on making and publishing games… and nobody knows about them.