You know what you're not looking hard enough & that's because ~Well I just "switched" it to 5k INR and below :3
a) You want us to spend that amount of time/effort which you apparently don't wanna do yourself :thumbsdown:
OR
b) You want the cheapest GPU that'll drive a number of games which is simply not possible in that tiny budget D:
either way here's your answer ~
https://www.google.co.in/search?q=R7+240
If even that doesn't work you then I guess you should remove the word gaming from the topic's title