version 2 by Jon Ingold
We can also consider when the landmark happened relative to the current time:
if emerging from the forest happened last turn ...
if reaching the city walls happened more than four turns ago ...
if emerging from the forest happened three minutes ago ...
The extension also provides some phrases for comparing times, which may be useful even if the landmark system isn't used.
if (time) is more than/less than (n) minutes ago
if (time) is (n) minutes ago
Note, landmarks are often going to look like actions, but cannot actually be actions -- you will need to choose names that don't conflict with other things in Inform.