I’ve made available a playable demo of Nightfall Hacker. Currently you can only move two different programs around a grid, but here it is. (I tried, but failed, to embed it in this page)
To play, select one of the spawn points, then select either Hack or Slingshot from the list. When you’ve spawned some programs, click the start button. To move a program, click it, then click one of the highlighted squares to move to it.