!!!! FOR EVERYONE HAVING THIS ISSUE !!!! solution is written bellow
after some research , found out this issue is due to weird setting of WebGL in Firefox, other WebGL content works but if it set strangely (still investigating update1) this could happen, seems the issue could be combination of setting up webgl like scaling or something and some other things like blend mode or pixelation,with combination of build in graphics card (intel in my case *cough cough* older notebooks) older windows and graphics drivers and so on , strangely too , in other browsers it works fine
SOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
solution #1 > install second browser, just for this game another browser (worth it ;) )
- most websites are optimized for chrome and chrome based browsers anyway so , installing
solution #2 > disabling WebGL in Firefox , just for this game (worth it ;) )
- tested in Firefox 80.0.1 64bit and for me it worked ,and you can change it afterwards back
- if someone got the same issue but doesn't work for them , please let me know to change this text,
- the game should use 2D canvas instead of WebGL (if you disable WebGL) and if not playing on some old old old old old old notebook or some old old old old smartphone without javascript support it should be fine (gonna test that one level with animated background )
FOR EVERYONE CURIOUS after looking in some of the code there are these keys (the canvas need to have the focus , meaning you have to click inside the game screen before using the keys)
F2 - turn on/off FPS counter and render mode (in code it's _switchFPSMeter() )
F3 - scale / stretch the game screen (in code it's _switchStretchMode())
F4 - switch full screen mode (in code it's _switchFullScreen() )
Z - (or Y if you have set up QWERTZ keyboard)- is confirming / entering (similar keys but NOT recommended by me to use SPACE BAR / ENTER keys) space bar is set in most browsers to scroll down so it can keep scrolling down while trying to confirm menu (may be not in full screen mode , need testing), and enter is not recommended (by me) for security reasons , there could happen a pop up window from some advertisement or what ever and accidentally open that window or worse
X - for entering and exiting menu similar key ESC
+ there is the thing with saving progress to your browser so if you have incognito mode or not allowed to have cookies or what ever stuff it may happen your progress will get lost and you have to speed run from start ;)
thanks to CaesarCub for his great games , have fun enjoy the game and don't forget to support CaesarCub