Extinction has five game modes to choose from. They differ from each other in several aspects, but the maps, enemies, and overall design of each mission remain the same. There are five main game modes: Single Player Campaign, Challenge, Skirmish, Daily Challenge, and Extinction. Specific game modes have been described in the following sections:
Single player campaign
You can check your current quest in the pause menu.
The single player campaign consists of 7 chapters, each of which is divided into several parts, resulting in a total of 34 missions in the game. In each of the missions, you have to complete one main task – this will allow you to move on to the next stage. In addition to the main tasks, you will also be able to complete additional tasks during each mission. Depending on the mission, this will be either one or three side tasks. Failure to complete any of the side objectives will not affect the success of the main mission. In the case of some chapters where another goal can be found, the goal itself is not fixed. Once you start the mission, a random target will be chosen at random. If you want to change the target, you need to return to the main menu and start the mission again.
Tests
In Challenge mode, your task is to save all civilians – and do it as quickly as possible.
The problems in the disappearance concern the rescue of a certain number of civilians. This is the main goal. Additional medals can be obtained by completing the task within a certain time. The important thing is that once you die, the mission will be over and you will need to restart it. You can access challenges from the campaign menu.
skirmish
In this mode, your task is to save civilians. Here you have no time limit, but you need to keep an eye on the number of civilians killed – if too many of them die, the mission will fail. Also, you can fight Raveni and smaller enemies before rescuing civilians to get more points.
Daily Challenges
The mode is similar to a shootout. The main difference is that you can compete with other players to earn the most points. The ratings of the best players for a given day are presented daily.
Extinction
A mode in which you will have one life and you will need to defeat as many enemies as possible and get as many points as possible. Points can be earned by saving civilians and fighting lesser enemies and Raveni. There are no time limits here. The mission ends when the hero is killed or the city is completely destroyed.
Interface
The interface in Extinction is very clear and easy to read. Only the most important information is displayed on the main screen, such as the map, health level, kill charge level, and city destruction level.
1 – Map
2 – Health level
3 – kill charge
4 – City destruction level
Source: https://guides.gamepressure.com