These are the kinds of things that should be sorted out when you found your company. :) For clarity, I will refer to the authoring tools and player as "Tools" to distinguish them from other software owned by the company (eg, the games").
Let's assume that you wrote the Tools before joining the company and that these Tools have not been changed since you joined the company. In this instance, you could argue that you still own the Tools and you let the company use them, a free license if you will. If you want to maintain ownership of the Tools, you could document this free license after the fact and hopefully your partners will agree to this.
If other employees modified the Tools or you modified the Tools after the company was founded, then it gets more complicated. The company presumably owns the work of the employees and also you as it relates to the company's products. You could argue that you as an individual and the company are joint owners of the Tools. If you want to maintain full ownership of the Tools, then you could
- buy out the company's part ownership, or
- give the company full ownership of the Tools in exchange for the company
giving you a perpetual license to use the Tools in any way that you want.
Note that either of these solutions could diminish the value of the company to a prospective buyer.
Also note that this is a complicated and very fact dependent situation so this answer should only be considered as very general background information and not something you should act on.
