The first ever Call of Duty has many elements which the newer CoD games keep coming back to, or just simply lost. The graphics might not look appealing today, and the AIs might look stupid, but this is where it all started, and look at how many good aspects of the game were simply lost as they kept making new games. For example, consider the battle of Starlinglad from the Russian campaign. Do we have that 'Victory or Death' charge with epic music in modern CoDs? No. Or the health pack system? No, these days you're an invincible sponge capable of soaking up millions of rounds. In terms of gameplay, this first CoD is still comparable or significantly better than the newer CoDs. Just play it if you haven't done so yet.