I don’t know about you guys but when I create a static runtime in 2.34 esc doesn’t close the window.
I can’t seem to make a dynamic runtime in 2.34 though
there is no dynamic runtime executable… so you can’t
the escape key WILL quit ONLY if the runtime is run fullscreen, windowed the user can probably just move the mouse [you can try to lock it into the window, but there are other ways to close it too which when running windowed aren’t blocked]
Mmhh last year someone posted a topic about this, and he archived to disable the ecs function in runtimes. No ide how, I should try a search. 
I’ve done it, download the blenderplayer that I build for linux and test it.
Here is the link: http://planeta.terra.com.br/informatica/projetomo/blenderplayer.tar.bz2
Copy and Paste.
Cu.
Mmhh I got something wrong, the topic I was talking about was using another way to exit a runtime. https://blenderartists.org/forum/viewtopic.php?t=13844&highlight=disable+esc
Not how to disable ecs. 
but well I found the thing I was telling about.