You are RNA polymerase, a globular protein loose inside the nucleus. Find the gene's entrance, read the template strand at speed, build a growing RNA chain, carry it through RNA processing, and escape through a nuclear pore.
Drive through the nucleoplasm until you spot the arch labelled PROMOTER. It's the only way onto the gene; the other loops are inactive chromatin.
The road is the template strand. Each stretch is painted with a DNA base. Before you leave the stretch, add the complementary RNA nucleotide, or transcription aborts.
After the terminator the transcript is capped, tailed and spliced. You pick one of three spliceosomes (alternative splicing); then you become the mRNA and fly the 5' cap to a nuclear pore. In the cytoplasm you become EF-Tu: deliver the right tRNA to each codon in the ribosome.
RNA has no thymine: where the template shows A, you add uracil. Press T and the race is over. Faster driving means less time per base; a transcription factor power-up (steer into it!) lets the polymerase drive itself at top speed for 10 s while you only pick bases. Grab a second one while the first is active and they stack into overdrive, faster than your top speed.
← → steer · ↑ gas · ↓ brake
U C A G add a nucleotide (keys or on-screen buttons)
As the mRNA or EF-Tu: ↑ ↓ climb / dive · Space boost
Translation: fly through a tRNA to pick it up (fly through another to swap), then into the ribosome's A site. Anticodons are written 3'→5' so they line up under the 5'→3' codon.