#R, 103 Bytes

A fairly straight forward implementation. Dice rolls are done by sum(sample(n,i)).

i=1;n=scan();while(i&i<=n){cat(i,'d',n,': ',s<-sum(sample(n,i)),'\n',sep='');i=ifelse(s<i*n/2,i-1,i+1)}

Test run

> i=1;n=scan();while(i&i<=n){cat(i,'d',n,': ',s<-sum(sample(n,i)),'\n',sep='');i=ifelse(s<i*n/2,i-1,i+1)}
1: 9
2: 
Read 1 item
1d9: 9
2d9: 14
3d9: 10
2d9: 14
3d9: 9
2d9: 9
3d9: 12
2d9: 7
1d9: 9
2d9: 11
3d9: 17
4d9: 18
5d9: 25
6d9: 29
7d9: 33
8d9: 43
9d9: 45
> 

R, 103 Bytes

A fairly straight forward implementation. Dice rolls are done by sum(sample(n,i)).

i=1;n=scan();while(i&i<=n){cat(i,'d',n,': ',s<-sum(sample(n,i)),'\n',sep='');i=ifelse(s<i*n/2,i-1,i+1)}

Test run

> i=1;n=scan();while(i&i<=n){cat(i,'d',n,': ',s<-sum(sample(n,i)),'\n',sep='');i=ifelse(s<i*n/2,i-1,i+1)}
1: 9
2: 
Read 1 item
1d9: 9
2d9: 14
3d9: 10
2d9: 14
3d9: 9
2d9: 9
3d9: 12
2d9: 7
1d9: 9
2d9: 11
3d9: 17
4d9: 18
5d9: 25
6d9: 29
7d9: 33
8d9: 43
9d9: 45
>