A gaseous fuel engine combines the efficiencies associated with high compression ratio engines with the attractiveness of fueling with natural gas. Each engine cylinder has an associated fuel injector positioned for direct injection and supplied with gaseous fuel from a high pressure common rail. A separate ignition prechamber is also supplied with natural gas and includes an ignition device. Hot gas generated by igniting a mixture of gaseous fuel and air in the prechamber are used to ignite a much larger charge of gaseous fuel injected into the engine cylinder from the fuel injector. The engine has a compression ratio greater than 14: to 1.