The source code wasn't provided for the challenge requiring the use of a decompiler or disassembler such as Ghidra, radare, ida or objdump. After reverse engineering the binary, it is evident through the use of the unsafe function gets in combination with a fixed size char array feature[16] that the code is vulnerable to a buffer overflow.
The binary features a section of code that isn't reachable through normal execution which is called 'deadcode', it's here that the system calls '/bin/sh' which spawns a bin shell. This is referenced in the challenge description by noting the "code isn't (a)live yet".
After identifying the value we need to set long code to access the deadcode and the size of the char array that the gets stores its value in (16 chars/bytes), we can start to build our exploit. By using 16 'A's we can fill the char array, then we have to overwrite the base pointer (RBP) which is 8 bytes, we can use 8 'B's to denote this. Finally, in little endian format we can overwrite the long variable code stored on the stack, this is: \xde\xc0\xad\xde.
Piecing this all together, we get AAAAAAAAAAAAAAAABBBBBBBB\xde\xc0\xad\xde. This can either be put into a solve script or exploited using echo as shown below.
Local execution:
(echo -e "AAAAAAAAAAAAAAAABBBBBBBB\xde\xc0\xad\xde";cat) | ./deadcode
Remote execution:
(echo -e "AAAAAAAAAAAAAAAABBBBBBBB\xde\xc0\xad\xde";cat) | nc <host> <port>