Image looks good. Unfortunately, I use only Macs. Therefore I cannot try it out due to this apparently being windows only. Nice work for your first time with Gosu and Ruby, welcome aboard!

Looks interesting so far! Glad you got some use from Releasy's :windows_folder builder!

I'd recommend you look at a higher level Gosu framework, such as Gamebox or Chingu, to make things easier for you once you add more functionality.

A few comments on the code, to help you along with Ruby in general:

Rather than using if/then/end on one line, we generally use the single conditional postfix this way:
close if button_down? KbEscape

Use two spaces rather than hard tab. Makes your code look a lot nicer when viewed online too.

if @obrot == :prawo then
We don't usually use then; It just isn't necessary. Also, that bit is crying out to be a case statement.

Rather than use your own #debug method, use Logger (standard library) or Log4r (gem) for logging.

for i in 0..2 do => (0..2).each do |i| (Although for might feel better if you are coming from another language, it is extremely limiting once you try to do a bit more with Ruby)

def block?(x,y); @map_main[(y/32)][(x/32)] != 0; end

Use ?: over if/then/else/end on one line (or put it on multiple lines).

print(Time.now.strftime("%H:%M:%S.%L") + " - " + message.to_s + "\n") => puts "#{Time.now.strftime("%H:%M:%S.%L")} - #{message}" (although I suggested using a logger for this).