The best tip I can offer for playing Cruel Arena is to stick using the crossbow, 1 mouse click = 1 arrow fired, you can fire as fast as you can tap and there is no reload. Just be aware if you are using a mouse to play the game, by the end of your first playthrough your wrist will be in severe pain.

During your first playthrough you want to aim for the "Welcome To Hell" achievement which pops when you reach level 30 (you do not have to complete it, just reach it). This takes approximately 30 mins and along the way you will earn all other achievements in the game other than "GIT GUD".

If you are struggling to get to level 30 the only other advice I can offer is to try and stay on the ground level in the middle as much as possible and try to avoid the far left or right of the screen for prolonged periods.

Welcome To Hell Achievement Video
The video was nearly 35 mins long and so level 5 to 30 have been sped up 300% to keep the video under 15 mins long.

After this first play through the only achievement remaining will be "GIT GUD", to obtain this all you need do is start up a new game and let yourself die 5 times before level 5.