There is a nice program that you can talk to by using this command in a shell: $ nc mercury.picoctf.net 35652, but it doesn't speak English...
Connecting to the port given with the netcat command gives us an output of a set of several integers. Shell command:
nc mercury.picoctf.net 35652
Output:
112
105
99
111
67
84
70
123
103
48
48
100
95
107
49
116
116
121
33
95
110
49
99
51
95
107
49
116
116
121
33
95
57
98
51
98
55
51
57
50
125
10
Seeing as all these numbers are in decimal range we throw them into CyberChef with the recipe "From Decimal" to decode into ascii giving us the flag. CyberChef Recipe: https://gchq.github.io/CyberChef/#recipe=From_Decimal('Line%20feed',false)&input=MTEyIAoxMDUgCjk5IAoxMTEgCjY3IAo4NCAKNzAgCjEyMyAKMTAzIAo0OCAKNDggCjEwMCAKOTUgCjEwNyAKNDkgCjExNiAKMTE2IAoxMjEgCjMzIAo5NSAKMTEwIAo0OSAKOTkgCjUxIAo5NSAKMTA3IAo0OSAKMTE2IAoxMTYgCjEyMSAKMzMgCjk1IAo1NyAKOTggCjUxIAo5OCAKNTUgCjUxIAo1NyAKNTAgCjEyNSAKMTAgCg
picoCTF{g00d_k1tty!_n1c3_k1tty!_9b3b7392}