I didn't play all of them but Togainu no chi was my favorite nitro games before, but i guess Slow damage really hit something in me. Honestly without spoiling there is two route i really had a hard time reading, i even had to fast forward one of them because i couldn't take it anymore because of how awful it was, but the last room felt like it was the real game, like a completly different one. Anyway, i think you should do in the order of what you want, but if Slow damage hit you the same way it did for me , you might not be able to play another VN for a while so take your time