𝘉𝘢𝘴𝘦 𝘋𝘦𝘧𝘦𝘯𝘴𝘦 2: 𝘔𝘰𝘯𝘴𝘵𝘦𝘳𝘴, released in 2008, is the direct sequel to 𝘉𝘢𝘴𝘦 𝘋𝘦𝘧𝘦𝘯𝘴𝘦 2, and is a classic Defense Flash game where you control a double-barrelled turret to protect a base from monster attacks.
As you stop their assaults, the monsters vary and become more resistant to shots.
Use the money gained to purchase some upgrades!
Good luck!