feat: implement game progression

Makefile

@@ -23,4 +23,7 @@ brain-calc:
 	./bin/brain-calc
 
 brain-gcd:
-	./bin/brain-gcd
+	./bin/brain-gcd
+
+brain-progression:
+	./bin/brain-progression

bin/brain-progression

@@ -0,0 +1,9 @@
+#!/usr/bin/env php
+<?php
+
+use function BrainGames\Engine\runBrainGame;
+
+require_once __DIR__ . '/../src/bootstrap.php';
+
+$module = 'ProgressionGame';
+runBrainGame($module);

src/Games/ProgressionGame.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace BrainGames\Games\EvenGame;
+
+use Exception;
+
+use const BrainGames\Utils\ModuleUtils\HANDLER_QUESTION;
+use const BrainGames\Utils\ModuleUtils\LOCATION_HANDLERS;
+use const BrainGames\Utils\ModuleUtils\LOCATION_SETTINGS;
+use const BrainGames\Utils\ModuleUtils\SETTING_RULES;
+
+return function ($module) {
+    $module[LOCATION_SETTINGS][SETTING_RULES] = 'What number is missing in the progression?';
+
+    $module[LOCATION_HANDLERS][HANDLER_QUESTION] = fn() => questionHandler();
+
+    return $module;
+};
+
+/**
+ * Returns a question and its expected answer.
+ *
+ * - 0: The question (string)
+ * - 1: The expected answer (string)
+ *
+ * @return array{
+ *     0: string,
+ *     1: string
+ * }
+ * @throws Exception
+ */
+function questionHandler(): array
+{
+    $lengthProgression = 10;
+    $step = random_int(2, 10);
+    $shift = random_int(1, 10);
+    $progression = range($shift, $shift + (($lengthProgression - 1) * $step), $step);
+    $guessIndex = random_int(0, 8);
+    $expectedAnswer = $progression[$guessIndex];
+    $progression[$guessIndex] = '..';
+    $question = implode(' ', $progression);
+    return [$question, $expectedAnswer];
+}