Space Race IV

Review — where we got to 5 min

You have a two-player obstacle race with a countdown. Everything today is a shape you have used already, on the biggest project of the level.

• The broadcast chain from the Quiz Show: one script finishes and calls the next.
• The race on switch from two lessons ago.
• An if inside an else, from the medal card.

Quick-fire

You beat your friend once. They say it was luck. What would settle it, and what has to change in your project?

Today’s Topic 3 min

• A round counter, and a referee who knows when the match is over
• Two win counters, one per player
• Three endings: blue, red, and a draw
• stop [all v] replaced by a broadcast, so the game can carry on

Learning outcome

By the end of this lesson you will be able to:

1. Run a fixed number of rounds one after the other.
2. Keep a score for two players at once.
3. Declare a champion, including when there is not one.

Learnt — rounds, scores, a champion 28 min

1 · The winner stops stopping everything

stop [all v] is the block in the way. Nothing is left running afterwards, so nothing can start a second race. Replace it with a message.

when I receive [new round v]
go to x: (-200) y: (70)
wait until <touching [Finish v]?>
change [blue wins v] by (1)
say [Blue takes it!] for (2) seconds
broadcast [round over v]
            

The referee hears round over and decides what happens next. That decision is an if / else, and it is the whole of the match.

when I receive [round over v]
set [race on v] to (0)
wait (3) seconds
if <(round) > (2)> then
  broadcast [match over v]
else
  broadcast [new round v]
end
            

2 · Two scores

Two players need two counters. Where they are SET is the interesting part, and it is the same rule as the Quiz Show’s best score.

Put a win counter in the right-hand column and every round wipes it, so the match is always 1–0 to whoever won last.

when I receive [new round v]
set [race on v] to (0)
change [round v] by (1)
say [3] for (1) seconds
say [2] for (1) seconds
say [1] for (1) seconds
set [race on v] to (1)
say [GO!] for (1) seconds
            

3 · Three endings

Blue can win, red can win, and — with an even number of rounds, or a round nobody finishes — it can be level. Every match needs all three.

when I receive [match over v]
start sound [Triumph v]
if <(blue wins) > (red wins)> then
  say [Blue is the champion!] for (4) seconds
else
  if <(red wins) > (blue wins)> then
    say [Red is the champion!] for (4) seconds
  else
    say [A draw! Race again.] for (4) seconds
  end
end
            

Basic — turn your race into a match 25 min

This is a rewiring job. Almost every block you need already exists; what changes is which hat it hangs from.

Step 1 — the three variables

1. Make blue wins, red wins and round.
2. Show all three.
3. Set all three to 0 on the referee’s green-flag stack.
4. End that stack with broadcast [new round v].

Step 2 — move the countdown

1. Change the referee’s countdown hat from when flag clicked to when I receive [new round v].
2. Add change [round v] by (1) near the top of it.
3. Press the flag. One countdown should run.

Step 3 — the winning scripts report

1. Change each rocket’s winning hat to when I receive [new round v].
2. Put the go to x: (-200) y: (70) block at the top of it.
3. Swap stop [all v] for broadcast [round over v].
4. Add change [blue wins v] by (1) before the message.

Step 4 — the referee decides

1. Build the round-over script on the referee.
2. Test it. Three countdowns should run, one after another.
3. Check the round counter reaches 3 and stops.

Step 5 — the champion

1. Build the match-over script with the if inside the else.
2. Play a whole match, driving both rockets yourself.
3. Play a second one and check everything starts from nothing.

A scoreboard you can read while flying

Players in the middle of a race should not have to squint at the corner to know the score.

• The score is visible during the race, not only between rounds.
• Which round it is, is on screen.
• Nothing covers a lane or a rocket.

Best of five, decided early

Make it best of five — and stop as soon as one player has won three, instead of playing races that cannot change anything.

• Up to five rounds.
• A player who reaches three wins ends the match there and then.
• A 3–0 match plays three races, not five.
• A 3–2 match plays all five.

Hand it to two strangers

The last challenge of Level 1. Two people who have never seen your game sit down and play a whole match. You say nothing.

• They work out which rocket is theirs.
• They work out which keys are theirs.
• They play three races without asking you anything.
• They know who won.

A handicap for the winner

A match between a fast player and a slow one is over after round one. Make winning a round cost you a little ground in the next.

• Winning a round moves your start line backwards for the next one.
• Losing does not.
• Nobody ever starts off the left of the Stage.
• The handicap resets at the start of a new match.

when I receive [new round v]
go to x: (blue start) y: (70)
wait until <touching [Finish v]?>
change [blue wins v] by (1)
change [blue start v] by (-15)
broadcast [round over v]
            

if <(blue start) < (-215)> then
  set [blue start v] to (-215)
end
            

Summary 5 min

Thirty-six lessons ago the cat moved ten steps; today two people play a three-round match against each other.

1. stop [all v] ends a project. A broadcast ends a ROUND.
2. A referee holds the counters and decides when the match is over.
3. Match scores live on the green flag; round state lives on the round.
4. Three endings, tested in order, and one of them is the draw.

What the six arcs covered

• Moving, turning, gliding, and the Stage’s coordinates.
• Costumes, backdrops, saying, sound, and two things happening at once.
• Events, loops, if, if / else, and the questions Sensing can ask.
• Variables: as a score, as a countdown, as a mood, and as a switch.
• Clones, broadcasts, and a game with a title screen and an ending.

Round

One race. A match is several of them.

Match

A set of rounds with a winner decided at the end.

Draw

Nobody won. It needs its own ending, even when it seems impossible.

Referee

The sprite that holds the rules. It is played by nobody.

Next lesson: a new arc — one key, one hop, and a game that never lets you stand still.