"Not fully tested" isn't something I like to hear in association with roller coasters, but here RollerCoaster Tycoon World (opens in new tab) is having a crack at Early Access.
Your £30/$50 (wince) buys "the core features and content of the game", including the campaign, sandbox and scenario modes, 10 coasters, 30 flat rides, 4 themes, "a full (albeit not fully balanced) simulation", park ops, various stalls and amenities, and terrain editor.
Publisher Atari describes it as "a full-featured gaming experience", but user reviews suggest otherwise, citing little improvement over the beta build, broken basics like road building, and sub-par looks compared with 2004's RollerCoaster Tycoon 3. I fear that 'Mostly Negative' rating will be hard to shift, particularly in light of delays (opens in new tab), a change of developer (opens in new tab) and the sudden switch to Early Access (opens in new tab) itself.
Planet Coaster (opens in new tab) looks the more inviting theme park sim currently, but at Frontier's steep early bird prices, you might be best off queuing a little longer.