Keyboard trainer

The following script is a game to learn typing Rebol keywords, you have to type the floating words before they reach the left side of the area.

Here the source code:

REBOL [
    Title: "Keyboard Trener"
    Date: 25-Mar-2006
    Version: 1.0.0
    File: %keyboar-trener.r
    Author: "Karol Gozlinski"
    Purpose: "Learn to write rebol words faster without looking at keyboard."
    Email: hali_tonic@o2.pl
]
random/seed now
dictionary: make block! 1000
foreach word first system/words [
  if all [
      value? to-word word
      not found? find to-string word "~"
      not block? word
      not object? word
      not image? word
  ][append dictionary to-string word ]
]
draw-dialect-block: []
screen-size: 400x128
movement-rate: 0:0:0.05
safty-area: 160
probability-adjustment: 2
if error? try [highscore: to-integer load %keyboard-trener-highscore][highscore: 0 ]
set-starting-parameters: does [
  probability: 1000
  score: 0
  stopped: false
  clear draw-dialect-block
  append draw-dialect-block [text 350x96 "Hello"]
  highscore-banner/font/color: yellow
]
view/title center-face layout [
  backdrop effect [ gradient 0x1 main-color linen ]
  across
  score-banner: vh2 left (screen-size/x / 2) bold yellow ""
  highscore-banner: vh2 right (screen-size/x / 2 - 10) bold yellow ""  
  below
  screen: image linen screen-size effect [draw draw-dialect-block] rate movement-rate feel [
      engage: func [face action event][
        if any [ stopped action <> 'time] [return]
        score-banner/text: join "Score : " next form 10000000 + score
        show score-banner
        if score > highscore [
            highscore: score
            highscore-banner/font/color: green
        ]
        highscore-banner/text: join "Highscore : " next form 10000000 + highscore
        show highscore-banner
        forskip draw-dialect-block 3 [
            if (draw-dialect-block/2/x: draw-dialect-block/2/x - 1) < 0 [
              clear draw-dialect-block
              append draw-dialect-block compose [
                  text ( screen-size / 2 - 40x10) "GAME OVER"
              ]
              stopped: true
              save %keyboard-trener-highscore highscore
            ]
        ]
        show screen
        if stopped [return]
        probability: probability + probability-adjustment
        if all [not empty? draw-dialect-block probability < random 100000] [return]
        empty-slots: make block! 20
        for y 0 screen-size/y 16 [append empty-slots y]
        remove back tail empty-slots
        foreach [feat pos word] draw-dialect-block [
            if (screen-size/x - pos/x) < safty-area [
              remove-each s empty-slots [ s = pos/y]
            ]
        ]
        if empty? empty-slots [return]
        append draw-dialect-block compose [
            text
            ( as-pair screen-size/x random/only empty-slots)
            ( lotto: random/only dictionary)
        ]
        probability: probability - power length? lotto 3
      ]
  ]
  text navy "INSTRUCTION : Write flying words before they hit left margin !!!"
  across
  input-field: field 225 [
      if all [ stopped empty? input-field/text][set-starting-parameters]
      remove-each [feat pos word] draw-dialect-block [
        either word = input-field/text [
            probability: probability + power length? input-field/text 3
            score: score + length? input-field/text
            true
        ][false]
      ]
      clear input-field/text
      focus input-field
  ]
  btn 80 linen "Restart" [set-starting-parameters]
  btn 80 linen "Quit" [quit]
  return
  text "(c) 2006 Karol Gozlinski"
  do [
      score-banner/saved-area: true
      highscore-banner/saved-area: true
      set-starting-parameters
      focus input-field
  ]
] {Keyboard Trener}