Infectonator

Infectonator (original version) is a classic pixel strategy Flash browser game developed by Toge Productions and published by Armor Games, released in December 2009. It is the first entry of the Infectonator series. Players act as a virus launcher, click to release zombie virus within the time limit and trigger chain reactions to turn civilians into zombies. Zombies will actively chase uninfected people to keep spreading the virus. Coins drop after infections, which can be spent to upgrade virus infectivity, zombie movement speed and durability, and unlock items like grenades. Each level requires a minimum number of infected people. Police and other units will try to contain the outbreak. Featuring simple pixel art and dark humor zombie theme, the game is fully controlled by mouse clicks. Its unique gameplay of creating zombie apocalypse made it one of the most popular Flash games in its era.

These games get the keyboard directly — the controls are whatever the game itself defines, usually in its own help or options screen. Some games show on-screen buttons on phones.