Doppleganger (UK) (1985) - Amstrad CPC - Adventure, Sci-Fi

Become a sorceress as you explore the Castle of Doom in an attempt to find some treasure. The element of thinking that appears in this game is that both you and your ghostly doppelgänger can go through some doors but not others, so to reach the same room, you and your alter ego often need to take different routes. There are also objects to collect, and watch out for the spiders that will drain your energy.