Hello Jose Antonio,
Thank you for contacting me. Please note that in a sentence where "more of" is used, it has to be followed by "than ... (2nd complement to subject) .. of".
I believe the example you provided is correct but it is incomplete as it lacks context. This can be resolved with the corrections below to add understanding to it:
Example 1: If you capture more of your opponents pieces than they capture of yours, then you will win.
N.B. When you begin a sentence with "If", it is vital that you use "then" in order to complete the sentence or carry across a point. Example 1 is only a basic sentence.
Example 2: In chess, If you can capture more of your opponents pieces than they capture of yours, you will win.
N.B. In Example 2, context (In chess) is provided at the beginning of the sentence and therefore gives a better understanding to the sentence. This sentence can be said to be an explanation.
Example 3:
Jorge - I can win the game!!
Jose Antonio - If you can capture more of your opponents pieces than they capture of yours.
N.B. The dialogue in Example 3 gives prior context to the use of the sentence and provides conditionality for Jorge to achieve a positive outcome.
All examples given above are all correct and complete. They are all dependent on context.
For any further questions, feel free to get in touch.
Thank you.