[ECO code C50]
White correctly declines 4.KtxKP?? (actually something of an instructive trap) and here his K-side Knight removes Black's knight on Q4(d4) instead, inviting 4..PxKt for 5.0-0 to gain a slight lead with a good prospect for an initiative. W-Alt.
White Black 1. P-K4 P-K4 2. Kt-KB3 Kt-QB3 3. B-B4 Kt-Q5!? 4. KtxKt
Example ends: Undo or Jump or Clear