BEST Win10 Chinese IME: PIME
Download link: https://github.com/osfans/PRIME/releases
LOL IME NOT displayed solution:
Add the following lines to ..\GameData\Apps\LoLTW\Game\DATA\Menu\IMEConfig.xml in ChineseSimplified section:
<imeName>中州韻輸入法 (PIME)</imeName>
<displayName>PIME</displayName>
<Tag>GFxIME_SogouPinyin</Tag>