CROWD NIFTY INDEX PREDICTION - Startup business , is it legal ??

Hi ,
I am planning to launch startup website businss to crowd nifty index daily contest .

Crowdd will predict the nifty index by paying an nominal entry fee of say 100 rs and predicts the value .
top 3 winners will be awarded with 90 percent of money which we recieved from overall crow users .
we take 10 percent as service charge from the payout .

All transactions will happen thru virtual points , only the payin and payout will be real money , example 1 rs = 1 point

this website will be purely for users to learn and check there confidence level on there technical /functional analysis .
and also to check control on greed/fear /emotional factors before they lose heavy money in real market with NSE/BSE stocks .

we also provide learning and training to users via online blogs,books and training materials .

Please let me know if this business model is legal for nifty index where no securties are really bought or exchanged ?
as far my research , this business model falls under category of "game of skill" .

you reply is highly appreciated .

Thanks
Gopi jayaraman

CROWD NIFTY INDEX PREDICTION - Startup business , is it legal ??