故事背景
未来，城市上空出现了虫洞。这个虫洞连接了未知世界。其中一个世界有一种生物不断侵入。一天神秘力量封锁了虫洞。只能少量生物通过。未知生物一心想大举入侵。不断攻击神秘力量。人类拿起武器，消灭未知生物。保卫城市。
In the future, wormholes appear in the city. This wormhole connects the unknown world. One of the world has a creature that is constantly invading. One day mysterious power blocked the wormhole. Only a small amount of organisms can pass. Unknown creatures are bent on invading. Constantly attack the mysterious power. Humans take up weapons and destroy unknown creatures. Defend the city.