The ROI would be (10,598 - 115, 698) / 115,698 = ~-90%

Is ROI profit/investment or revenue/investment?

http://www.investopedia.com/terms/r/returnoninvestment.asp says its the first one.

No, 10% ROI would be $115,698 + %10. What you have here is more like a -90% ROI.

Spent: $100 Won: 0$ Win/Loss: $-100 Balance $0

ROI: ~1,000,000%

if ROI was 10%, winnings would have been ~$127k