Xibalba

Xibalba drops you in the enemy-filled Mayan Underworld, where danger lurks around every corner. With catacombs, jungles, and other claustrophobic levels, a variety of hazards and foes await.

• The game features three weapons, six enemy types, 6 levels, and wealth of traps to evade and power-ups to collect.

Besides classics like Doom and Marathaon, you won't find many old arcade first-person shooters on mobile, especially ones made from the ground up for touch. Xibalba is an exception to that, and its pixel-y, retro action is currently available for free.