Re: [MAINNET]"MimbleWimble", we cast this spell so mote it be. GRIMM was born.
Windows 10. Also I don't like the idea that wallet comes packaged inside installer, I would prefer if it was just zip file which you extract into some folder. Anyway I just formatted hard drive and installed fresh OS. If it had any malware, they have lived short 
It's open source. You can build it from source and use (github releases https://github.com/freenetcoder/grimm/releases). This code fore miner build-in if interest - https://github.com/freenetcoder/grimm/tree/master/3rdparty/opencl-miner. The websites like this https://newrewardcoins.com - checking for malware all wallets