  We provide a self-contained introduction to finite extensive games with
perfect information. In these games players proceed in turns having, at each
stage, finitely many moves to their disposal, each play always ends, and in
each play the players have complete knowledge of the previously made moves.
Almost all discussed results are well-known, but often they are not presented
in an optimal form. Also, they usually appear in the literature aimed at
economists or mathematicians, so the algorithmic or logical aspects are
underrepresented.
