Make a Bubble-wrap simulator
C (Windows), 260 248 bytes

#import&lt;windows.h&gt;
i,j,l,r;b(w,h){char*s=malloc(l=w*h+h);for(i=h;i--;*s++=10)for(j=w;j--;*s++=i%2^j%2?79:45);*(s-1)=0;s-=l;for(srand(time(0));j&gt;system("cls")+puts(s)-2;j&gt;-1?s[j]=88:0)for(Sleep(1000),r=rand(),j=-2,i=r+l*2;--i-r;j=s[i%l]==79?i%l:j);}