An internal combustion engine system includes an internal combustion engine for combustion of gaseous fuel and has a combustion chamber at least partially delimited by a cylinder; a reciprocating piston moveable within said cylinder between a bottom dead centre and a top dead centre, said reciprocating piston having a piston top end comprising a piston bowl intended to form part of the combustion chamber The piston bowl has a plurality of spaced-apart protrusions circumferentially distributed around a centre axis on a bottom section of the piston bowl, each one of the spaced-apart protrusions extending a substantial part in a radial direction towards the centre axis; a controllable fuel injector injects gaseous fuel with a low injection pressure into the combustion chamber and toward the piston bowl; and a controller controls the controllable fuel injector to inject at least one gaseous fuel jet towards the bottom section of the piston bowl during a fuel injection period occurring prior to an ignition event of the gaseous fuel.