Someone else mention Urban Terror [0]. Similar in style to CS but fast paced. Also because it's Quake3 based it has all the strafe jumping and highly rewarding movement. Haven't played it in years, but back then it was good fun. Whilst the aiming itself is not necessarily much easier, it is more forgiving. In CS you have one encounter and the round is over for you. With this I'm pretty sure there are various deathmatch modes and much more relaxed respawn rules.

[0] https://www.urbanterror.info/home/