Das Erbe

The point&click adventure “Das Erbe” (=”the inheritance”) puts you into the
place of a youngster whose uncle dies to leave not only three millions in
cash, but also an old house. The catch? You’ll only get to the money, if
you’re able to renovate the mansion without any environmental burdens.

The game was published by German environmental authorities back in 1991 and
has since been distributed for free.

Das Erbe