The Vindicator Amstrad CPC

Alien forces wreak havoc on our planet. The earth torn and blasted in what seemed the final war. But enough survived to uphold the laws of justice and revenge. Now one man must face th final enemy. He is the Vindicator. Across a tortured landscape against incredible odds he must battle through to the enemy stronghold, down into a maze-like corridor filled with mutated guardians until he reaches the inner sanctum of the dark overlord to strike the final blow of retribution. — Cassette cover

Trivia

In the UK, the game Vindicator! by Imagine was marketed as Green Beret II.