Of anxiety and overlap

There are many general mechanics reused again and again, and IMHO that's no problem. For example, worker placement gets used in many games, and why not? If you tried hard to avoid all common mechanics, you'd most probably either reinvent one you weren't aware of, or invent something not workable. Modifying an existing mechanic is easier, finding an original combination of existing mechanics may work best.

IMHO, you can reuse whatever you want, as long as some substantial part of your game is original and also the game as whole feels original.

I wouldn't like to play your game if it felt just like game X (unless it would be a much better version of X which is hard to achieve). If the game felt a bit similar to X, a bit similar to Y, and yet had something original, it'd be fine for me.

Yeah plumb, the other guys have got it down. But I would say that we probably need some more info on your specific game
We must allow first of all for a definition of "mechanic" eg, "draw a card" can technically be seen to be a mechanic, and of course if your game has card drawing, I would probably not have a go that another game I have played also asks me to draw a card and hence you are copying .

In all honesty nothing is ever new, only the way it comes across at the end is of any difference. There will always be a few games that make up all if the mechanics if your game, but as long as players don't get cheesed off "omg, this is just a copy of x " you'll be ok

Tbh even if it is VERY similar it will be ok, eg pc game Bioshock is a spiritual successor of system shock, likewise torchwood with dialog, as Kong as its a new game, and doesn't take the milky with how close it is, you will be perfectly fine, and remember there is an argument to be made that people PREFER game styles athat they have played before: quarriors to dominion and the reason that expansions tend entire well much better than the main games due to an existing fan basev

Hope I've helped. Cog