I don't think touche translates backwards like that.
To give it an ''olde touche'', yes. Gramatically it will be today's English, but with a few olde words. That's all. It shouldn't be something like correct language from Shakesbeer's time. It will be today's English with and old touch.
Hundley is right, though. If you don't know what you're doing yourself, then it won't turn out well. If you simply want Middle Engrish in there, then simply throw in some words. If you want it to actually sound like Middle English, then you're going to have to have a clue about what you're doing. Not knowing what you're doing is the number one cause of completed video games just absolutely failing -- the gameplay won't matter, the story itself won't matter, hell, the graphics won't even help if your game is misguided and most of it is obtained through using a translator, even though I'm certain none exist.
If you want it to turn out good and actually strike the older feel that such a use of language should, then you just have to know how to do it yourself. Honestly, researching a topic like this wouldn't take a long time -- You should already know what the words mean, the only issue is grammatical structure, which is maybe a single days worth of reading, if even that much!