Here is the full list of all 19 Red Risk achievements.
Kill 100 Infected.
Reach level 5.
Reach level 4.
Reach level 3.
Reach level 2.
Enter the arena.
Reach level 6.
Reach level 7.
Reach level 8.
Reach level 9.
Reach level 10.
Stay alive for 1000 seconds.
Stay alive for 2500 seconds.
Stay alive for 5000 seconds.
Kill 1000 Infected.
Kill 2500 Infected.
Survive your first tournament.
Survive five tournaments.
Survive ten tournaments.