I've been able to get LunaTranslator to hook into a visual novel by running them both in the same Bottle. Textractor worked in the past too. Not sure about other types of games though, I've only tested a few visual novels. And getting the visual novel itself working in the Bottle can be a bit of a crapshoot. So far I've had luck using the soda runner for my Bottles, and then in the Bottle settings, add the environment variable LC_ALL=ja_JP.UTF-8 and set the language to "Japanese".

If you just want translation then LunaTranslator should be enough, but I do sentence mining, so I have LunaTranslator and a VN running inside a Bottle, and LunaTranslator connecting to RenjiXD texthooker page (running in a browser outside Bottles) using the websocket method (in LunaTranslator enable "network service", then in RenjiXD texthooker page settings connect to ws://localhost:2333/api/ws/text/origin, more info here). Then I can scan words using Yomi-tan and add them to my Anki flashcards. I did have to write some hacky scripts to add screenshots and audio to my flashcards as well, if anybody is interested I can share them.

What about Windows makes translating easier?

Wine?