I don't think we'll be able to tell you if any specific thing is your talent given by God. That's between you and Him. And chances are pretty good that you have multiple gifts from Him, not just one. That said, I think it comes down to things like balance and intention a lot in life. If you feel God is calling you to give a certain portion of your resources to missions, you should do that to the best of your ability. But remember 2 Cor 9:7
: "Each of you should give what you have decided in your heart to give, not reluctantly or under compulsion, for God loves a cheerful giver." We have to be careful we're not giving out of guilt or doing so reluctantly. If that happens, our heart isn't in the right place.
Simultaneously I think the same thing can be semi-applied to your game development. If you're giving your time and energy to glorify God in terms of game production, that can be done cheerfully and with your heart as well. Finding a balance between paying for assets and doing hard work yourself is essential. Do what is yours to do, but be careful not to spend your time doing what isn't yours to do. If you have a skill for coding, code for the Glory of God. If you don't have a skill for art (and don't feel a calling to pursue such a thing) then support those who DO have that gift. Remember, they need to eat too!
Perhaps a lot of it comes down to discernment. Maybe you can seek out assets by people who you feel are doing good work vs. making a quick buck? Both sets of people exist, and supporting the former group is a wise thing, yeah? Sometimes you won't be able to tell, and that's when going to God in prayer can help. Ask Him to guide you, and see who he puts in front of you. Amazing things can happen when we put it all in His hands instead of our own.
In the end, remember He loves you no matter what, and trying your best for Him is sometimes more important than the outcome. After all, if God wanted a specific RPG done in an exact certain way, a word from His mouth could create it. He revels in the fact that YOU, his beloved, want to create like He does. He stands and watches with joy while you work on your creation. Don't fret, He loves you. Have peace and freedom in that and go and create with your whole heart, whether you responsibly buy assets or not.
Do you have a link to your dev blog or anything? As a fellow indie dev (on the art side here, actually!) I enjoy seeing what others are working on! Let me know!