(shameless plug alert)<p>This is how my WIP (verrrry WIP) game engine written in Guile Scheme works.  It is built explicitly to enable iterative, live development.<p>2 year old video of a precursor to the current project: <a href="https:&#x2F;&#x2F;dthompson.us&#x2F;functional-reactive-programming-in-scheme-with-guile-2d.html" rel="nofollow">https:&#x2F;&#x2F;dthompson.us&#x2F;functional-reactive-programming-in-sche...</a><p>Simple example program: <a href="https:&#x2F;&#x2F;git.dthompson.us&#x2F;sly.git&#x2F;blob&#x2F;HEAD:&#x2F;examples&#x2F;simple.scm" rel="nofollow">https:&#x2F;&#x2F;git.dthompson.us&#x2F;sly.git&#x2F;blob&#x2F;HEAD:&#x2F;examples&#x2F;simple....</a><p>More complicated minesweeper example: <a href="https:&#x2F;&#x2F;git.dthompson.us&#x2F;sly.git&#x2F;blob&#x2F;HEAD:&#x2F;examples&#x2F;mines&#x2F;mines.scm" rel="nofollow">https:&#x2F;&#x2F;git.dthompson.us&#x2F;sly.git&#x2F;blob&#x2F;HEAD:&#x2F;examples&#x2F;mines&#x2F;m...</a><p>Home page: <a href="https:&#x2F;&#x2F;dthompson.us&#x2F;pages&#x2F;software&#x2F;sly.html" rel="nofollow">https:&#x2F;&#x2F;dthompson.us&#x2F;pages&#x2F;software&#x2F;sly.html</a><p>Hoping to get a 0.2 release out the door in time for the Lisp Game Jam coming up in April.