If you describe a situation or activity as unforgiving, you mean that it causes a lot of people to experience great difficulty or failure, even people who deserve to succeed.
2. not to be placated or appeased or moved by entreaty;
"grim determination""grim necessity""Russia's final hour, it seemed, approached with inexorable certainty""relentless persecution""the stern demands of parenthood"
3. harsh and severe;
"I hope I'm not being uncharitable but he really is a bore""unjust and uncharitable criticism"