Step into the epic world of strategic defense with 'The Sentinel'! Prepare yourself for an exhilarating and challenging gaming experience that will put your tactical skills to the test. At the heart of this tower defense game, you will discover your castle, a sanctuary of glory and fortitude that is under the imminent threat of a horde of voracious invaders. The action kicks off with a simple cannon, a loyal guardian that stands ready to defend your castle against the forces of darkness. Face initial waves of enemies, each more ruthless than the last. But make no mistake, your journey is merely beginning. As time progresses, new horizons unfold with a vast array of upgrades at your disposal. Hone your weapons, unlock powerful abilities, and deploy defense mechanisms to repel the invaders. The true key to victory in 'The Sentinel' lies in strategy. Choose wisely which upgrades to apply and when to do so. Do you prefer reinforcing your defenses to withstand a massive assault, or opting for precise attacks to eliminate the most dangerous foes before they draw near? The decision is yours and will shape the fate of your castle. Don't allow your castle to fall into the hands of the enemies! Join the battle in 'The Sentinel' and prove yourself as a strategist. Command your defenses, enhance your weaponry, and safeguard your kingdom with courage and intelligence. Adventure awaits, victory beckons - are you prepared to face the challenge? About the gameplay. The game begins with the player choosing one of the 20 available upgrades. Shortly after, the game starts, and the player controls a small cannon positioned at the top of the castle using the keyboard arrows. This cannon continuously fires spheres that fall due to gravity. These spheres collide with various balloons rising on the screen. Each balloon has a number indicating how many hits it needs to burst. When a balloon reaches a certain height on the screen, the value marked on it is subtracted from the player's cannon life. There is a bar at the bottom of the screen that fills over time. Every time the bar is fully charged, the player can choose another upgrade. The game ends when the cannon's life count reaches zero, or when the player survives against waves of enemies for 15 minutes. Additionally, there's an upgrade system where the more points the player accumulates during matches, the more upgrades they can choose at the beginning of the game, starting with 1 and going up to a maximum of 10.