Is it possible to set initial state (at runtime) to something which is different from what was passed in FSM_INITIAL_STATE? about tinyfsm

[digint]

I would not recommend this, as you are breaking basic state machine rules with this.
That said, you could probably write your own set_initial_state specialization, something like:

#define FSM_INITIAL_STATE_FROM_DB(_FSM, _STATE_1, _STATE_2)  \
namespace tinyfsm {                                                   \
  template<> void Fsm< _FSM >::set_initial_state(void) {              \
    if(dbvalue == 1) \
      current_state_ptr = &_state_instance< _STATE_1 >::value;            \
    else if(dbvalue == 2 \
      current_state_ptr = &_state_instance< _STATE_2 >::value;            \
  }                                                                   \
}

You can "hard" set a state at any time by modifying current_state_ptr.