I would suggest the following
AMD Ryzen 3600X ( ~ 17-19k)
Asus/MSI b550 wifi motherboard ( ~ 10-12k , will be cheaper if you don't need wifi chipset)
8GB*2 Corsair Vengeance DDR4 3600 ( ~7- 8k)
Seasonic/Antec 650W SMPS ( ~ 5-6k)
Cabinet ( not sure which are recommended now, Codsair Carbide series are quiet good and set you back by 3-5k)
I would say the above are basic components to build a decent PC future proof for some time at least and would cost about 50k.
The pending components now would be Monitor , KB & Mouse , UPS and Graphics card. Let me start with
i) GPU - If you are open to used market you can get a Nvidia GTX 1070 Ti (18k)/ 1080 TI ( 23-25K) , RTX 2070 (27-30K)/ RTX 2080 (34-40K) , but would have almost no warranty remaining. From the newer generation cards though the cheapest would be a 3060ti which will set you back by atleast 40k-42k. So you will need to take a call on which way you want to proceed
ii) Keyboard and mouse - Few gaming combos are available for as low as 1.5k from Red Dragon and other brands, should be good enough
iii) Monitor - If purpose is casual gaming , you will get decent monitors upto/within 10k , if you need high refresh rate monitors with VA/IPS panels will cost you about 18-20k.
iv) UPS - 1KVA UPS will cost you about 4k-5k i believe.
Personally would suggest to go the used GPU route and upgrade if needed anytime in the future.