REBOL [ title: "Invaders (GUI version)" date: 11-Jan-2016 file: %invaders-gui.r author: Nick Antonaccio purpose: { The draw dialect is not used in this example, only VID GUI, so it's short and full featured for a tiny example. A video explaining the code is at https://youtu.be/NbbHRaG3K8c Taken from http://re-bol.com/short_rebol_examples.r ; KEYS: a=left s=right space=fire ; VARS: b boxes m missile s invaders l player e end-func p speed d dir } ] e: func[x][alert x q]s:[2 3 4 5 6 32 33 34 35 36]p: .1 m: 0 l: 586 d: 1 g:[ key #"a"[if l > 571 [do rejoin["b"l"/image:{}"]l: l - 1]] key #"s"[if l < 600 [do rejoin["b"l"/image:{}"]l: l + 1]] key #" "[if m < 1[m: l]] across origin 0x0 space 1x1 backcolor snow ] repeat i 600[ repend g[to-set-word join"b"i 'box 20x20] if i // 30 = 0[append g 'return] ] w: view/new layout g forever[ remove find s m attempt[do rejoin["b"m"/image:{}"]]if s =[][e"Win!"] repeat i length? s[do rejoin["b"s/:i"/image:{}"]] oldd: d foreach i s[if i // 30 = 0[d: no] if i // 30 = 1[d: yes]] if oldd <> d[repeat i length? s[s/(:i): s/:i + 30]] p: p - .0002 repeat i length? s[ either d[s/(:i): s/:i + 1][s/(:i): s/:i - 1] if error? try[do rejoin["b"s/:i"/image: stop.gif"]][e"Lose!"] ]attempt[do rejoin["b"m"/text:{}"]m: m - 30 do rejoin["b"m"/text:{|}"]] do rejoin["b"l"/image: info.gif"] show w if not viewed? w[q] wait p ]