Firstly you need to end the simulation, otherwise the sim will just run forever and eventually the process will get killed. You can do this by adding a call to $finish:
#10000 $finish
Secondly you need to create a VCD. Once you've added the above code EDAPlayground will give you a helpful error message:
No *.vcd file found. EPWave will not open. Did you use '$dumpfile("dump.vcd"); $dumpvars;'?
So by adding the following code:
initial begin
$dumpfile("dump.vcd");
$dumpvars;
#10000 $finish;
end
Your example code runs and is viewable in the waveform viewer: http://www.edaplayground.com/x/3v2