Ganito kasi yan, every system or software na ginagawa will start from using only your own local drives. So basically your code will still completely run kahit na  simulation lng iyan or your final output even without a "Network".

What's the purpose of connecting your system to a network? whether it is Local Are Network, Wide Area Network, World Wide Web which is the Global Network or the Internet. Ang main purpose nyan is to obviously to connect your system or software to other people who shares the same network.

So for example is to what happens to @OP yung nagawa nyang program is not connected to a network so basically siya lng din makakapag test ng program nya. But what if gusto mo rin i try? Dyan na papasok ang network. Pde i upload ni OP yung program nya sa isang hosting at pde kana din mag test through it.