coso.awk

# part 1
awk '
    /forward/ { x += $2 }
    /up/ {y-=$2}
    /down/ {y+=$2}
    END {print x*y}
' input.txt
# part 2
awk '
    /forward/ {x+=$2;y+=$2*aim}
    /up/ {aim-=$2}
    /down/ {aim+=$2}
    END {print x*y}
' input.txt